diff --git a/internal/frontend/bridge-gui/BridgeMonitor.cpp b/internal/frontend/bridge-gui/BridgeMonitor.cpp
index 817c8510..a66cfaf0 100644
--- a/internal/frontend/bridge-gui/BridgeMonitor.cpp
+++ b/internal/frontend/bridge-gui/BridgeMonitor.cpp
@@ -56,7 +56,7 @@ QString BridgeMonitor::locateBridgeExe()
 
     for (QString const &dir: dirs)
     {
-        QFileInfo const fileInfo = QDir(dir).absoluteFilePath(exeName);
+        QFileInfo const fileInfo(QDir(dir).absoluteFilePath(exeName));
         if (fileInfo.exists() && fileInfo.isFile() && fileInfo.isExecutable())
             return fileInfo.absoluteFilePath();
     }
@@ -91,7 +91,7 @@ void BridgeMonitor::run()
         emit started();
 
         QProcess p;
-        p.start(exePath_);
+        p.start(exePath_, QStringList());
         p.waitForStarted();
 
         while (!p.waitForFinished(100))
diff --git a/internal/frontend/bridge-gui/CMakeLists.txt b/internal/frontend/bridge-gui/CMakeLists.txt
index eca72337..c6ac2d36 100644
--- a/internal/frontend/bridge-gui/CMakeLists.txt
+++ b/internal/frontend/bridge-gui/CMakeLists.txt
@@ -17,15 +17,30 @@
 
 cmake_minimum_required(VERSION 3.22)
 
-set(CMAKE_OSX_ARCHITECTURES x86_64) # needs to be set before the first project() directive.
-
 #We rely on vcpkg for to get gRPC+Protobuf
 if (NOT DEFINED ENV{VCPKG_ROOT})
     message(FATAL_ERROR "vcpkg is required. Install vcpkg and define VCPKG_ROOT to point the the vcpkg installation folder. (e.g. ~/vcpkg/")
 endif()
+
+
+# For now we support only a single architecture for macOS (ARM64 or x86_64). We need to investigate how to build universal binaries with vcpkg.
 if (APPLE)
-    set(VCPKG_TARGET_TRIPLET x64-osx)
+    if (NOT DEFINED CMAKE_OSX_ARCHITECTURES)
+        execute_process(COMMAND "uname" "-m" OUTPUT_VARIABLE UNAME_RESULT OUTPUT_STRIP_TRAILING_WHITESPACE)
+        set(CMAKE_OSX_ARCHITECTURES ${UNAME_RESULT} CACHE STRING "osx_architectures")
+    endif()
+
+    if (CMAKE_OSX_ARCHITECTURES STREQUAL "arm64")
+        message(STATUS "Building for Apple Silicon Mac computers")
+        set(VCPKG_TARGET_TRIPLET arm64-osx)
+    elseif (CMAKE_OSX_ARCHITECTURES STREQUAL "x86_64")
+        message(STATUS "Building for Intel based Mac computers")
+        set(VCPKG_TARGET_TRIPLET x64-osx)
+    else ()
+        message(FATAL_ERROR "Unknown value for CMAKE_OSX_ARCHITECTURE. Please use one of \"arm64\" and \"x86_64\". Multiple architectures are not supported.")
+    endif ()
 endif()
+
 if  (WIN32)
     set(VCPKG_TARGET_TRIPLET x64-mingw-static)
 endif()
@@ -33,16 +48,15 @@ set(CMAKE_TOOLCHAIN_FILE "$ENV{VCPKG_ROOT}/scripts/buildsystems/vcpkg.cmake" CAC
 
 
 project(bridge-gui LANGUAGES CXX)
-if (APPLE) # On macOS, we have some Objective-C++ code in DockIcon to deal with ... the dock icon.
+if (APPLE) # On macOS, we have some Objective-C++ code in DockIcon to deal with the dock icon.
     enable_language(OBJC OBJCXX)
 endif()
 
-if (NOT DEFINED ENV{QT5DIR})
-    message(FATAL_ERROR "QT5DIR needs to be defined and point to the root of your Qt5 folder (e.g. /Users/MyName/Qt/5.10.1/clang_64).")
+if (NOT DEFINED ENV{QT6DIR})
+    message(FATAL_ERROR "QT6DIR needs to be defined and point to the root of your Qt 6 folder (e.g. /Users/MyName/Qt/6.3.1/clang_64).")
 endif()
 
-
-set(CMAKE_PREFIX_PATH $ENV{QT5DIR} ${CMAKE_PREFIX_PATH})
+set(CMAKE_PREFIX_PATH $ENV{QT6DIR} ${CMAKE_PREFIX_PATH})
 set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_AUTOMOC ON)
@@ -61,7 +75,7 @@ if (APPLE) # We need to link the Cocoa framework for the dock icon.
 endif()
 
 
-find_package(Qt5 COMPONENTS
+find_package(Qt6 COMPONENTS
     Core
     Quick
     Qml
@@ -136,10 +150,10 @@ include_directories(${CMAKE_CURRENT_SOURCE_DIR})
 target_precompile_headers(bridge-gui PRIVATE Pch.h)
 
 target_link_libraries(bridge-gui
-    Qt5::Core
-    Qt5::Quick
-    Qt5::Qml
-    Qt5::QuickControls2
+    Qt6::Core
+    Qt6::Quick
+    Qt6::Qml
+    Qt6::QuickControls2
     protobuf::libprotobuf
     gRPC::grpc++
     )
diff --git a/internal/frontend/bridge-gui/README.md b/internal/frontend/bridge-gui/README.md
index d0c23301..4d19b041 100644
--- a/internal/frontend/bridge-gui/README.md
+++ b/internal/frontend/bridge-gui/README.md
@@ -1,5 +1,6 @@
 ## Prerequisite
 
+### Linux (debian and derivates)
 ```` bash
 sudo apt install build-essential
 sudo apt install tar curl zip unzip
@@ -7,22 +8,63 @@ sudo apt install linux-headers-$(uname -r)
 sudo apt install mesa-common-dev libglu1-mesa-dev
 ````
 
-## Define Qt5DIR
+### macOS & WIndows
 
-```` bash
-export QT5DIR=/opt/Qt/5.13.0/gcc_64
-````
+Coming soon...
 
-## install vcpkg and define VCPKG_ROOT
 
-```` bash
+###  Define QT6DIR
+
+``` bash
+export QT6DIR=/opt/Qt/6.3.1/gcc_64
+```
+
+### install vcpkg and define VCPKG_ROOT
+
+``` bash
 git clone https://github.com/Microsoft/vcpkg.git
 ./vcpkg/bootstrap-vcpkg.sh 
 export VCPKG_ROOT=$PWD/vcpkg
-````
+```
 
 ## install grpc & protobuf
 
-```` bash
+``` bash
 ./vcpkg install grpc
-````
+```
+
+## Building
+
+A simple script is provided that run the appropriate CMake command.
+
+``` bash
+./build.sh
+``` 
+
+## Running
+
+Simply run from the cmake build folder (`cmake-build-debug` by default) 
+``` bash
+./bridge-gui
+```
+
+`bridge-gui` will launch the `bridge` executable that it will try to locate in
+
+- The working directory.
+- The application directory.
+- `cmd/Desktop-Bridge/`, `../cmd/Desktop-Bridge/`,  `../../cmd/Desktop-Bridge` 
+(up to five parent folders above the current folder are inspected).
+
+you can specify the location of the bridge executable using the `-b` or 
+`--bridge-exe-path` command-line parameter:
+
+``` bash
+./bridge-gui -b "~/bin/bridge"
+```
+
+you can also ask bridge-gui to connect to an already running instance of `bridge`
+using the `-a` or `--attach` command line parameter.
+
+``` bash
+./bridge-gui -a
+```
diff --git a/internal/frontend/bridge-gui/main.cpp b/internal/frontend/bridge-gui/main.cpp
index 9d43c875..5bbd5cd7 100644
--- a/internal/frontend/bridge-gui/main.cpp
+++ b/internal/frontend/bridge-gui/main.cpp
@@ -28,8 +28,6 @@
 //****************************************************************************************************************************************************
 std::shared_ptr<QGuiApplication> initQtApplication(int argc, char *argv[])
 {
-    // Note the two following attributes must be set before instantiating the QCoreApplication/QGuiApplication class.
-    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling, false);
     if (QSysInfo::productType() != "windows")
         QCoreApplication::setAttribute(Qt::AA_UseSoftwareOpenGL);
 
@@ -69,22 +67,22 @@ QQmlComponent *createRootQmlComponent(QQmlApplicationEngine &engine)
 {
     QString const qrcQmlDir = "qrc:/qml";
 
-    qmlRegisterType<QMLBackend>("CppBackend", 1, 0, "QMLBackend");
-    qmlRegisterType<UserList>("CppBackend", 1, 0, "UserList");
-    qmlRegisterType<User>("CppBackend", 1, 0, "User");
+    qmlRegisterSingletonInstance("Proton", 1, 0, "Backend", &app().backend());
+    qmlRegisterType<UserList>("Proton", 1, 0, "UserList");
+    qmlRegisterType<User>("Proton", 1, 0, "User");
 
     auto rootComponent = new QQmlComponent(&engine, &engine);
 
     engine.addImportPath(qrcQmlDir);
     engine.addPluginPath(qrcQmlDir);
-
-    QQuickStyle::addStylePath(qrcQmlDir);
     QQuickStyle::setStyle("Proton");
 
     rootComponent->loadUrl(QUrl(qrcQmlDir + "/Bridge.qml"));
     if (rootComponent->status() != QQmlComponent::Status::Ready)
+    {
+        app().log().error(rootComponent->errorString());
         throw Exception("Could not load QML component");
-
+    }
     return rootComponent;
 }
 
@@ -178,9 +176,8 @@ int main(int argc, char *argv[])
         app().backend().init();
 
         QQmlApplicationEngine engine;
-        QQmlComponent *rootComponent = createRootQmlComponent(engine);
-
-        QObject *rootObject = rootComponent->beginCreate(engine.rootContext());
+        std::unique_ptr<QQmlComponent> rootComponent(createRootQmlComponent(engine));
+        std::unique_ptr<QObject> rootObject(rootComponent->beginCreate(engine.rootContext()));
         if (!rootObject)
             throw Exception("Could not create root object.");
         rootObject->setProperty("backend", QVariant::fromValue(&app().backend()));
@@ -188,17 +185,23 @@ int main(int argc, char *argv[])
 
         BridgeMonitor *bridgeMonitor = app().bridgeMonitor();
         bool bridgeExited = false;
+        QMetaObject::Connection connection;
         if (bridgeMonitor)
-            QObject::connect(bridgeMonitor, &BridgeMonitor::processExited, [&](int returnCode) {
+            connection = QObject::connect(bridgeMonitor, &BridgeMonitor::processExited, [&](int returnCode) {
                 // GODT-1671 We need to find a 'safe' way to check if brige crashed and restart instead of just quitting. Is returnCode enough?
-                bridgeExited = true;
+                bridgeExited = true;// clazy:exclude=lambda-in-connect
                 qGuiApp->exit(returnCode);
             });
 
-        int result = QGuiApplication::exec();
+        int const result = QGuiApplication::exec();
 
+        QObject::disconnect(connection);
         app().grpc().stopEventStream();
-        app().backend().clearUserList(); // required for proper exit. We may want to investigate why at some point.
+
+        // We manually delete the QML components to avoid warnings error due to order of deletion of C++ / JS objects and singletons.
+        rootObject.reset();
+        rootComponent.reset();
+
         if (!bridgeExited)
             closeBridgeApp();
 
diff --git a/internal/frontend/bridge-gui/qml/AccountDelegate.qml b/internal/frontend/bridge-gui/qml/AccountDelegate.qml
index 001a7761..6b5668d5 100644
--- a/internal/frontend/bridge-gui/qml/AccountDelegate.qml
+++ b/internal/frontend/bridge-gui/qml/AccountDelegate.qml
@@ -15,11 +15,11 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
 
-import Proton 4.0
+import Proton
 
 Item {
     id: root
diff --git a/internal/frontend/bridge-gui/qml/AccountView.qml b/internal/frontend/bridge-gui/qml/AccountView.qml
index 67e7f2ec..774987d4 100644
--- a/internal/frontend/bridge-gui/qml/AccountView.qml
+++ b/internal/frontend/bridge-gui/qml/AccountView.qml
@@ -15,16 +15,15 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
 
-import Proton 4.0
+import Proton
 
 Item {
     id: root
     property ColorScheme colorScheme
-    property var backend
     property var notifications
     property var user
 
@@ -117,7 +116,7 @@ Item {
                             Button {
                                 Layout.alignment: Qt.AlignTop
                                 colorScheme: root.colorScheme
-                                icon.source: "icons/ic-trash.svg"
+                                icon.source: "/qml/icons/ic-trash.svg"
                                 secondary: true
                                 onClicked: {
                                     if (!root.user) return
@@ -227,8 +226,8 @@ Item {
                         Configuration {
                             colorScheme: root.colorScheme
                             title: qsTr("IMAP")
-                            hostname:   root.backend.hostname
-                            port:       root.backend.portIMAP.toString()
+                            hostname:   Backend.hostname
+                            port:       Backend.portIMAP.toString()
                             username:   configuration.currentAddress
                             password:   root.user ? root.user.password : ""
                             security:   "STARTTLS"
@@ -237,11 +236,11 @@ Item {
                         Configuration {
                             colorScheme: root.colorScheme
                             title: qsTr("SMTP")
-                            hostname : root.backend.hostname
-                            port     : root.backend.portSMTP.toString()
+                            hostname : Backend.hostname
+                            port     : Backend.portSMTP.toString()
                             username : configuration.currentAddress
                             password : root.user ? root.user.password : ""
-                            security : root.backend.useSSLforSMTP ? "SSL" : "STARTTLS"
+                            security : Backend.useSSLforSMTP ? "SSL" : "STARTTLS"
                         }
                     }
                 }
diff --git a/internal/frontend/bridge-gui/qml/Banner.qml b/internal/frontend/bridge-gui/qml/Banner.qml
index 740a975b..7332f21e 100644
--- a/internal/frontend/bridge-gui/qml/Banner.qml
+++ b/internal/frontend/bridge-gui/qml/Banner.qml
@@ -15,13 +15,13 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
-import QtQuick.Controls.impl 2.12
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
+import QtQuick.Controls.impl
 
-import Proton 4.0
-import Notifications 1.0
+import Proton
+import Notifications
 
 Popup {
     id: root
@@ -119,13 +119,13 @@ Popup {
 
                         switch (root.notification.type) {
                             case Notification.NotificationType.Info:
-                            return "./icons/ic-info-circle-filled.svg"
+                            return "/qml/icons/ic-info-circle-filled.svg"
                             case Notification.NotificationType.Success:
-                            return "./icons/ic-info-circle-filled.svg"
+                            return "/qml/icons/ic-info-circle-filled.svg"
                             case Notification.NotificationType.Warning:
-                            return "./icons/ic-exclamation-circle-filled.svg"
+                            return "/qml/icons/ic-exclamation-circle-filled.svg"
                             case Notification.NotificationType.Danger:
-                            return "./icons/ic-exclamation-circle-filled.svg"
+                            return "/qml/icons/ic-exclamation-circle-filled.svg"
                         }
                     }
                 }
diff --git a/internal/frontend/bridge-gui/qml/Bridge.qml b/internal/frontend/bridge-gui/qml/Bridge.qml
index ce6dbc18..af36cb2b 100644
--- a/internal/frontend/bridge-gui/qml/Bridge.qml
+++ b/internal/frontend/bridge-gui/qml/Bridge.qml
@@ -15,13 +15,13 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQml 2.12
-import QtQuick 2.13
-import QtQuick.Window 2.13
-import Qt.labs.platform 1.1
+import QtQml
+import QtQuick
+import QtQuick.Window
+import Qt.labs.platform
 
-import Proton 4.0
-import Notifications 1.0
+import Proton
+import Notifications
 
 QtObject {
     id: root
@@ -33,12 +33,10 @@ QtObject {
         return Math.max(lower_limit, Math.min(upper_limit, num))
     }
 
-    property var backend
     property var title: "Proton Mail Bridge"
 
     property Notifications _notifications: Notifications {
         id: notifications
-        backend: root.backend
         frontendMain: mainWindow
         frontendStatus: statusWindow
         frontendTray: trayIcon
@@ -49,19 +47,18 @@ QtObject {
         visible: false
 
         title: root.title
-        backend: root.backend
         notifications: root._notifications
 
         onVisibleChanged: {
-            backend.dockIconVisible = visible
+            Backend.dockIconVisible = visible
         }
 
         Connections {
-            target: root.backend
-            onCacheUnavailable: {
+            target: Backend
+            function onCacheUnavailable() {
                 mainWindow.showAndRise()
             }
-            onColorSchemeNameChanged: root.setColorScheme()
+            function onColorSchemeNameChanged(scheme) { root.setColorScheme() }
         }
     }
 
@@ -70,7 +67,6 @@ QtObject {
         visible: false
 
         title: root.title
-        backend: root.backend
         notifications: root._notifications
 
         onShowMainWindow: {
@@ -93,7 +89,7 @@ QtObject {
         }
 
         onQuit: {
-            backend.quit()
+            Backend.quit()
         }
 
         property rect screenRect
@@ -157,14 +153,14 @@ QtObject {
         visible: true
         icon.source: getTrayIconPath()
         icon.mask: true // make sure that systems like macOS will use proper color
-        tooltip: `${root.title} v${backend.version}`
-        onActivated: {
+        tooltip: `${root.title} v${Backend.version}`
+        onActivated: function(reason) {
             function calcStatusWindowPosition() {
                 // On some platforms (X11 / Plasma) Qt does not provide icon position and geometry info.
                 // In this case we rely on cursor position
                 var iconRect = Qt.rect(geometry.x, geometry.y, geometry.width, geometry.height)
                 if (geometry.width == 0 && geometry.height == 0) {
-                    var mousePos = backend.getCursorPos()
+                    var mousePos = Backend.getCursorPos()
                     iconRect.x = mousePos.x
                     iconRect.y = mousePos.y
                     iconRect.width = 0
@@ -229,7 +225,7 @@ QtObject {
         }
 
         function getTrayIconPath() {
-            var color = backend.goos == "darwin" ? "mono" : "color" 
+            var color = Backend.goos == "darwin" ? "mono" : "color"
 
             var level = "norm"
             if (_systrayfilter.topmost) {
@@ -245,25 +241,24 @@ QtObject {
                     break;
                 }
             }
-
-            return `./icons/systray-${color}-${level}.png`
+            return `qrc:/qml/icons/systray-${color}-${level}.png`
         }
     }
 
     Component.onCompleted: {
-        if (!root.backend) {
-            console.log("backend not loaded")
+        if (!Backend) {
+            console.log("Backend not loaded")
         }
 
         root.setColorScheme()
 
 
-        if (!root.backend.users) {
+        if (!Backend.users) {
             console.log("users not loaded")
         }
 
-        var c = root.backend.users.count
-        var u = root.backend.users.get(0)
+        var c = Backend.users.count
+        var u = Backend.users.get(0)
         // DEBUG
         if (c != 0) {
             console.log("users non zero", c)
@@ -280,15 +275,15 @@ QtObject {
             }
         }
 
-        if (root.backend.showOnStartup) {
+        if (Backend.showOnStartup) {
             mainWindow.showAndRise()
         }
 
-        root.backend.guiReady()
+        Backend.guiReady()
     }
 
     function setColorScheme() {
-        if (root.backend.colorSchemeName == "light") ProtonStyle.currentStyle = ProtonStyle.lightStyle
-        if (root.backend.colorSchemeName == "dark") ProtonStyle.currentStyle = ProtonStyle.darkStyle
+        if (Backend.colorSchemeName == "light") ProtonStyle.currentStyle = ProtonStyle.lightStyle
+        if (Backend.colorSchemeName == "dark") ProtonStyle.currentStyle = ProtonStyle.darkStyle
     }
 }
diff --git a/internal/frontend/bridge-gui/qml/BridgeTest/UserControl.qml b/internal/frontend/bridge-gui/qml/BridgeTest/UserControl.qml
index 50e64390..dc7700c3 100644
--- a/internal/frontend/bridge-gui/qml/BridgeTest/UserControl.qml
+++ b/internal/frontend/bridge-gui/qml/BridgeTest/UserControl.qml
@@ -15,19 +15,18 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQml 2.12
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.13
+import QtQml
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
 
-import Proton 4.0
+import Proton
 
 ColumnLayout {
     id: root
 
     property var user
     property var userIndex
-    property var backend
 
     spacing : 5
 
@@ -65,9 +64,9 @@ ColumnLayout {
                 }
 
                 if (checked) {
-                    if (user === backend.loginUser) {
-                        var newUserObject = backend.userComponent.createObject(backend, {username: user.username, loggedIn: true, setupGuideSeen: user.setupGuideSeen})
-                        backend.users.append( { object: newUserObject } )
+                    if (user === Backend.loginUser) {
+                        var newUserObject = Backend.userComponent.createObject(Backend, {username: user.username, loggedIn: true, setupGuideSeen: user.setupGuideSeen})
+                        Backend.users.append( { object: newUserObject } )
 
                         user.username = ""
                         user.resetLoginRequests()
@@ -120,7 +119,7 @@ ColumnLayout {
             enabled: user !== undefined //&& user.isLoginRequested && !user.isLogin2FARequested && !user.isLogin2PasswordProvided
 
             onClicked: {
-                root.backend.loginUsernamePasswordError("")
+                Backend.loginUsernamePasswordError("")
                 user.resetLoginRequests()
             }
         }
@@ -130,7 +129,7 @@ ColumnLayout {
             text: "free user error"
             enabled: user !== undefined //&& user.isLoginRequested
             onClicked: {
-                root.backend.loginFreeUserError()
+                Backend.loginFreeUserError()
                 user.resetLoginRequests()
             }
         }
@@ -140,7 +139,7 @@ ColumnLayout {
             text: "connection error"
             enabled: user !== undefined //&& user.isLoginRequested
             onClicked: {
-                root.backend.loginConnectionError("")
+                Backend.loginConnectionError("")
                 user.resetLoginRequests()
             }
         }
@@ -163,7 +162,7 @@ ColumnLayout {
 
             enabled: user !== undefined //&& user.isLoginRequested && !user.isLogin2FARequested && !user.isLogin2PasswordRequested
             onClicked: {
-                root.backend.login2FARequested(user.username)
+                Backend.login2FARequested(user.username)
                 user.isLogin2FARequested = true
             }
         }
@@ -174,7 +173,7 @@ ColumnLayout {
 
             enabled: user !== undefined //&& user.isLogin2FAProvided && !(user.isLogin2PasswordRequested && !user.isLogin2PasswordProvided)
             onClicked: {
-                root.backend.login2FAError("")
+                Backend.login2FAError("")
                 user.isLogin2FAProvided = false
             }
         }
@@ -185,7 +184,7 @@ ColumnLayout {
 
             enabled: user !== undefined //&& user.isLogin2FAProvided && !(user.isLogin2PasswordRequested && !user.isLogin2PasswordProvided)
             onClicked: {
-                root.backend.login2FAErrorAbort("")
+                Backend.login2FAErrorAbort("")
                 user.resetLoginRequests()
             }
         }
@@ -208,7 +207,7 @@ ColumnLayout {
 
             enabled: user !== undefined //&& user.isLoginRequested && !user.isLogin2PasswordRequested && !(user.isLogin2FARequested && !user.isLogin2FAProvided)
             onClicked: {
-                root.backend.login2PasswordRequested("")
+                Backend.login2PasswordRequested("")
                 user.isLogin2PasswordRequested = true
             }
         }
@@ -219,7 +218,7 @@ ColumnLayout {
 
             enabled: user !== undefined //&& user.isLogin2PasswordProvided && !(user.isLogin2FARequested && !user.isLogin2FAProvided)
             onClicked: {
-                root.backend.login2PasswordError("")
+                Backend.login2PasswordError("")
 
                 user.isLogin2PasswordProvided = false
             }
@@ -231,7 +230,7 @@ ColumnLayout {
 
             enabled: user !== undefined //&& user.isLogin2PasswordProvided && !(user.isLogin2FARequested && !user.isLogin2FAProvided)
             onClicked: {
-                root.backend.login2PasswordErrorAbort("")
+                Backend.login2PasswordErrorAbort("")
                 user.resetLoginRequests()
             }
         }
@@ -243,7 +242,7 @@ ColumnLayout {
             text: "Login Finished"
 
             onClicked: {
-                root.backend.loginFinished(0+loginFinishedIndex.text)
+                Backend.loginFinished(0+loginFinishedIndex.text)
                 user.resetLoginRequests()
             }
         }
@@ -261,7 +260,7 @@ ColumnLayout {
             text: "Already logged in"
 
             onClicked: {
-                root.backend.loginAlreadyLoggedIn(0+loginAlreadyLoggedInIndex.text)
+                Backend.loginAlreadyLoggedIn(0+loginAlreadyLoggedInIndex.text)
                 user.resetLoginRequests()
             }
         }
diff --git a/internal/frontend/bridge-gui/qml/BridgeTest/UserList.qml b/internal/frontend/bridge-gui/qml/BridgeTest/UserList.qml
index effe4bc1..0d42f4c8 100644
--- a/internal/frontend/bridge-gui/qml/BridgeTest/UserList.qml
+++ b/internal/frontend/bridge-gui/qml/BridgeTest/UserList.qml
@@ -15,17 +15,16 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.13
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
 
-import Proton 4.0
+import Proton
 
 ColumnLayout {
     id: root
 
     property ColorScheme colorScheme
-    property var backend
 
     property alias currentIndex: usersListView.currentIndex
     ListView {
@@ -33,7 +32,7 @@ ColumnLayout {
         Layout.fillHeight: true
         Layout.preferredWidth: 200
 
-        model: backend.usersTest
+        model: Backend.usersTest
         highlightFollowsCurrentItem: true
 
         delegate: Item {
@@ -74,16 +73,16 @@ ColumnLayout {
             text: "+"
 
             onClicked: {
-                var newUserObject = backend.userComponent.createObject(backend)
-                newUserObject.username = backend.loginUser.username.length > 0 ? backend.loginUser.username : "test@protonmail.com"
+                var newUserObject = Backend.userComponent.createObject(Backend)
+                newUserObject.username = Backend.loginUser.username.length > 0 ? Backend.loginUser.username : "test@protonmail.com"
                 newUserObject.loggedIn = true
-                newUserObject.setupGuideSeen = true // backend.loginUser.setupGuideSeen
+                newUserObject.setupGuideSeen = true // Backend.loginUser.setupGuideSeen
 
-                backend.loginUser.username = ""
-                backend.loginUser.loggedIn = false
-                backend.loginUser.setupGuideSeen = false
+                Backend.loginUser.username = ""
+                Backend.loginUser.loggedIn = false
+                Backend.loginUser.setupGuideSeen = false
 
-                backend.users.append( { object: newUserObject } )
+                Backend.users.append( { object: newUserObject } )
             }
         }
         Button {
@@ -93,8 +92,8 @@ ColumnLayout {
             enabled: usersListView.currentIndex != 0
 
             onClicked: {
-                // var userObject = backend.users.get(usersListView.currentIndex - 1)
-                backend.users.remove(usersListView.currentIndex - 1)
+                // var userObject = Backend.users.get(usersListView.currentIndex - 1)
+                Backend.users.remove(usersListView.currentIndex - 1)
                 // userObject.deleteLater()
             }
         }
diff --git a/internal/frontend/bridge-gui/qml/BridgeTest/UserModel.qml b/internal/frontend/bridge-gui/qml/BridgeTest/UserModel.qml
index 138db61e..1ca58a82 100644
--- a/internal/frontend/bridge-gui/qml/BridgeTest/UserModel.qml
+++ b/internal/frontend/bridge-gui/qml/BridgeTest/UserModel.qml
@@ -15,7 +15,7 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQml.Models 2.12
+import QtQml.Models
 
 ListModel {
     // overriding get method to ignore any role and return directly object itself
diff --git a/internal/frontend/bridge-gui/qml/Bridge_test.qml b/internal/frontend/bridge-gui/qml/Bridge_test.qml
index 35442b4c..9c454929 100644
--- a/internal/frontend/bridge-gui/qml/Bridge_test.qml
+++ b/internal/frontend/bridge-gui/qml/Bridge_test.qml
@@ -15,22 +15,22 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQml 2.12
-import QtQuick 2.13
-import QtQuick.Window 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.13
+import QtQml
+import QtQuick
+import QtQuick.Window
+import QtQuick.Layouts
+import QtQuick.Controls
 
-import QtQml.Models 2.12
+import QtQml.Models
 
-import Qt.labs.platform 1.1
+import Qt.labs.platform
 
-import Proton 4.0
+import Proton
 
 import "./BridgeTest"
-import BridgePreview 1.0
+import BridgePreview
 
-import Notifications 1.0
+import Notifications
 
 Window {
     id: root
diff --git a/internal/frontend/bridge-gui/qml/BugReportView.qml b/internal/frontend/bridge-gui/qml/BugReportView.qml
index 891b2bca..39f68289 100644
--- a/internal/frontend/bridge-gui/qml/BugReportView.qml
+++ b/internal/frontend/bridge-gui/qml/BugReportView.qml
@@ -15,11 +15,11 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
 
-import Proton 4.0
+import Proton
 
 SettingsView {
     id: root
@@ -122,7 +122,7 @@ SettingsView {
             text: qsTr("View logs")
             secondary: true
             colorScheme: root.colorScheme
-            onClicked: Qt.openUrlExternally(root.backend.logsPath)
+            onClicked: Qt.openUrlExternally(Backend.logsPath)
         }
     }
 
@@ -137,7 +137,7 @@ SettingsView {
         font.weight: ProtonStyle.fontWeight_400
         font.pixelSize: ProtonStyle.caption_font_size
         font.letterSpacing: ProtonStyle.caption_letter_spacing
-        // No way to set lineHeight: Style.caption_line_height
+        // No way to set lineHeight: ProtonStyle.caption_line_height
         selectionColor: root.colorScheme.interaction_norm
         selectedTextColor: root.colorScheme.text_invert
         wrapMode: Text.WordWrap
@@ -161,13 +161,16 @@ SettingsView {
             submit()
         }
 
-        Connections {target: root.backend; onReportBugFinished: sendButton.loading = false }
+        Connections {
+            target: Backend
+            function onReportBugFinished() { sendButton.loading = false }
+        }
     }
 
     function setDefaultValue() {
         description.text = ""
         address.text = root.selectedAddress
-        emailClient.text = root.backend.currentEmailClient
+        emailClient.text = Backend.currentEmailClient
         includeLogs.checked = true
     }
 
@@ -178,7 +181,7 @@ SettingsView {
 
     function submit() {
         sendButton.loading = true
-        root.backend.reportBug(
+        Backend.reportBug(
             description.text,
             address.text,
             emailClient.text,
diff --git a/internal/frontend/bridge-gui/qml/Configuration.qml b/internal/frontend/bridge-gui/qml/Configuration.qml
index ac7471bd..e7f8a6ab 100644
--- a/internal/frontend/bridge-gui/qml/Configuration.qml
+++ b/internal/frontend/bridge-gui/qml/Configuration.qml
@@ -15,12 +15,12 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
-import QtQuick.Controls.impl 2.12
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
+import QtQuick.Controls.impl
 
-import Proton 4.0
+import Proton
 
 Rectangle {
     id: root
diff --git a/internal/frontend/bridge-gui/qml/ConfigurationItem.qml b/internal/frontend/bridge-gui/qml/ConfigurationItem.qml
index 60327598..f9d694ac 100644
--- a/internal/frontend/bridge-gui/qml/ConfigurationItem.qml
+++ b/internal/frontend/bridge-gui/qml/ConfigurationItem.qml
@@ -15,12 +15,12 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
-import QtQuick.Controls.impl 2.12
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
+import QtQuick.Controls.impl
 
-import Proton 4.0
+import Proton
 
 Item {
     id: root
@@ -61,7 +61,7 @@ Item {
             }
 
             ColorImage {
-                source: "icons/ic-copy.svg"
+                source: "/qml/icons/ic-copy.svg"
                 color: root.colorScheme.text_norm
                 height: root.colorScheme.body_font_size
                 sourceSize.height: root.colorScheme.body_font_size
diff --git a/internal/frontend/bridge-gui/qml/ContentWrapper.qml b/internal/frontend/bridge-gui/qml/ContentWrapper.qml
index 2beddd30..65501965 100644
--- a/internal/frontend/bridge-gui/qml/ContentWrapper.qml
+++ b/internal/frontend/bridge-gui/qml/ContentWrapper.qml
@@ -15,18 +15,17 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
 
-import Proton 4.0
-import Notifications 1.0
+import Proton
+import Notifications
 
 Item {
     id: root
     property ColorScheme colorScheme
 
-    property var backend
     property var notifications
 
     signal showSetupGuide(var user, string address)
@@ -66,7 +65,6 @@ Item {
                         Layout.alignment: Qt.AlignHCenter
 
                         colorScheme: leftBar.colorScheme
-                        backend: root.backend
                         notifications: root.notifications
 
                         notificationWhitelist: Notifications.Group.Connection | Notifications.Group.ForceUpdate
@@ -93,7 +91,7 @@ Item {
 
                         horizontalPadding: 0
 
-                        icon.source: "./icons/ic-question-circle.svg"
+                        icon.source: "/qml/icons/ic-question-circle.svg"
 
                         onClicked: rightContent.showHelpView()
                     }
@@ -113,7 +111,7 @@ Item {
 
                         horizontalPadding: 0
 
-                        icon.source: "./icons/ic-cog-wheel.svg"
+                        icon.source: "/qml/icons/ic-cog-wheel.svg"
 
                         onClicked: rightContent.showGeneralSettings()
                     }
@@ -162,7 +160,7 @@ Item {
                         radius: ProtonStyle.account_row_radius
                     }
 
-                    model: root.backend.users
+                    model: Backend.users
                     delegate: Item {
                         width: leftBar.width - 2*accounts._leftRightMargins
                         implicitHeight: children[0].implicitHeight + children[0].anchors.topMargin + children[0].anchors.bottomMargin
@@ -178,13 +176,13 @@ Item {
                             anchors.rightMargin: 12
 
                             colorScheme: leftBar.colorScheme
-                            user: root.backend.users.get(index)
+                            user: Backend.users.get(index)
                         }
 
                         MouseArea {
                             anchors.fill: parent
                             onClicked: {
-                                var user = root.backend.users.get(index)
+                                var user = Backend.users.get(index)
                                 accounts.currentIndex = index
                                 if (!user) return
                                 if (user.loggedIn) {
@@ -227,7 +225,7 @@ Item {
 
                         horizontalPadding: 0
 
-                        icon.source: "./icons/ic-plus.svg"
+                        icon.source: "/qml/icons/ic-plus.svg"
 
                         onClicked: {
                             signIn.username = ""
@@ -250,12 +248,11 @@ Item {
 
                 AccountView { // 0
                     colorScheme: root.colorScheme
-                    backend: root.backend
                     notifications: root.notifications
                     user: {
                         if (accounts.currentIndex < 0) return undefined
-                        if (root.backend.users.count == 0) return undefined
-                        return root.backend.users.get(accounts.currentIndex)
+                        if (Backend.users.count == 0) return undefined
+                        return Backend.users.get(accounts.currentIndex)
                     }
                     onShowSignIn: {
                         signIn.username = this.user.username
@@ -280,7 +277,7 @@ Item {
                             signIn.abort()
                             rightContent.showAccount()
                         }
-                        icon.source: "icons/ic-arrow-left.svg"
+                        icon.source: "/qml/icons/ic-arrow-left.svg"
                         secondary: true
                         horizontalPadding: 8
                     }
@@ -296,13 +293,11 @@ Item {
                         Layout.fillHeight: true
 
                         colorScheme: root.colorScheme
-                        backend: root.backend
                     }
                 }
 
                 GeneralSettings { // 2
                     colorScheme: root.colorScheme
-                    backend: root.backend
                     notifications: root.notifications
 
                     onBack: {
@@ -312,7 +307,6 @@ Item {
 
                 KeychainSettings { // 3
                     colorScheme: root.colorScheme
-                    backend: root.backend
 
                     onBack: {
                         rightContent.showGeneralSettings()
@@ -321,7 +315,6 @@ Item {
 
                 PortSettings { // 4
                     colorScheme: root.colorScheme
-                    backend: root.backend
 
                     onBack: {
                         rightContent.showGeneralSettings()
@@ -330,7 +323,6 @@ Item {
 
                 SMTPSettings { // 5
                     colorScheme: root.colorScheme
-                    backend: root.backend
 
                     onBack: {
                         rightContent.showGeneralSettings()
@@ -339,7 +331,6 @@ Item {
 
                 LocalCacheSettings { // 6
                     colorScheme: root.colorScheme
-                    backend: root.backend
                     notifications: root.notifications
 
                     onBack: {
@@ -349,7 +340,6 @@ Item {
 
                 HelpView { // 7
                     colorScheme: root.colorScheme
-                    backend: root.backend
 
                     onBack: {
                         rightContent.showAccount()
@@ -358,11 +348,10 @@ Item {
 
                 BugReportView { // 8
                     colorScheme: root.colorScheme
-                    backend: root.backend
                     selectedAddress: {
                         if (accounts.currentIndex < 0) return ""
-                        if (root.backend.users.count == 0) return ""
-                        var user = root.backend.users.get(accounts.currentIndex)
+                        if (Backend.users.count == 0) return ""
+                        var user = Backend.users.get(accounts.currentIndex)
                         if (!user) return ""
                         return user.addresses[0]
                     }
@@ -389,10 +378,10 @@ Item {
                 function showBugReport          () { rightContent.currentIndex = 8 }
 
                 Connections {
-                    target: root.backend
+                    target: Backend
 
-                    onLoginFinished: rightContent.showAccount(index)
-                    onLoginAlreadyLoggedIn: rightContent.showAccount(index)
+                    function onLoginFinished(index) { rightContent.showAccount(index) }
+                    function onLoginAlreadyLoggedIn(index) { rightContent.showAccount(index) }
                 }
             }
         }
diff --git a/internal/frontend/bridge-gui/qml/DebugWrapper.qml b/internal/frontend/bridge-gui/qml/DebugWrapper.qml
index 7bfb241d..b9e9e592 100644
--- a/internal/frontend/bridge-gui/qml/DebugWrapper.qml
+++ b/internal/frontend/bridge-gui/qml/DebugWrapper.qml
@@ -15,8 +15,8 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Controls 2.12
+import QtQuick
+import QtQuick.Controls
 
 import "."
 import "./Proton"
diff --git a/internal/frontend/bridge-gui/qml/GeneralSettings.qml b/internal/frontend/bridge-gui/qml/GeneralSettings.qml
index b0ea78d7..f5380a4a 100644
--- a/internal/frontend/bridge-gui/qml/GeneralSettings.qml
+++ b/internal/frontend/bridge-gui/qml/GeneralSettings.qml
@@ -15,12 +15,12 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.13
-import QtQuick.Controls.impl 2.13
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
+import QtQuick.Controls.impl
 
-import Proton 4.0
+import Proton
 
 SettingsView {
     id: root
@@ -43,8 +43,8 @@ SettingsView {
         text: qsTr("Automatic updates")
         description: qsTr("Bridge will automatically update in the background.")
         type: SettingsItem.Toggle
-        checked: root.backend.isAutomaticUpdateOn
-        onClicked: root.backend.toggleAutomaticUpdate(!autoUpdate.checked)
+        checked: Backend.isAutomaticUpdateOn
+        onClicked: Backend.toggleAutomaticUpdate(!autoUpdate.checked)
 
         Layout.fillWidth: true
     }
@@ -55,14 +55,14 @@ SettingsView {
         text: qsTr("Open on startup")
         description: qsTr("Bridge will open upon startup.")
         type: SettingsItem.Toggle
-        checked: root.backend.isAutostartOn
+        checked: Backend.isAutostartOn
         onClicked: {
             autostart.loading = true
-            root.backend.toggleAutostart(!autostart.checked)
+            Backend.toggleAutostart(!autostart.checked)
         }
         Connections{
-            target: root.backend
-            onToggleAutostartFinished: {
+            target: Backend
+            function onToggleAutostartFinished() {
                 autostart.loading = false
             }
         }
@@ -76,12 +76,12 @@ SettingsView {
         text: qsTr("Beta access")
         description: qsTr("Be among the first to try new features.")
         type: SettingsItem.Toggle
-        checked: root.backend.isBetaEnabled
+        checked: Backend.isBetaEnabled
         onClicked: {
             if (!beta.checked) {
                 root.notifications.askEnableBeta()
             } else {
-                root.backend.toggleBeta(false)
+                Backend.toggleBeta(false)
             }
         }
 
@@ -92,7 +92,7 @@ SettingsView {
         ColorImage {
             Layout.alignment: Qt.AlignTop
 
-            source: root._isAdvancedShown ? "icons/ic-chevron-up.svg" : "icons/ic-chevron-down.svg"
+            source: root._isAdvancedShown ? "/qml/icons/ic-chevron-up.svg" : "/qml/icons/ic-chevron-down.svg"
             color: root.colorScheme.interaction_norm
             height: root.colorScheme.body_font_size
             sourceSize.height: root.colorScheme.body_font_size
@@ -118,13 +118,13 @@ SettingsView {
 
     SettingsItem {
         id: keychains
-        visible: root._isAdvancedShown && root.backend.availableKeychain.length > 1
+        visible: root._isAdvancedShown && Backend.availableKeychain.length > 1
         colorScheme: root.colorScheme
         text: qsTr("Change keychain")
         description: qsTr("Change which keychain Bridge uses as default")
         actionText: qsTr("Change")
         type: SettingsItem.Button
-        checked: root.backend.isDoHEnabled
+        checked: Backend.isDoHEnabled
         onClicked: root.parent.showKeychainSettings()
 
         Layout.fillWidth: true
@@ -137,8 +137,8 @@ SettingsView {
         text: qsTr("Alternative routing")
         description: qsTr("If Proton’s servers are blocked in your location, alternative network routing will be used to reach Proton.")
         type: SettingsItem.Toggle
-        checked: root.backend.isDoHEnabled
-        onClicked: root.backend.toggleDoH(!doh.checked)
+        checked: Backend.isDoHEnabled
+        onClicked: Backend.toggleDoH(!doh.checked)
 
         Layout.fillWidth: true
     }
@@ -150,8 +150,8 @@ SettingsView {
         text: qsTr("Dark mode")
         description: qsTr("Choose dark color theme.")
         type: SettingsItem.Toggle
-        checked: root.backend.colorSchemeName == "dark"
-        onClicked: root.backend.changeColorScheme( darkMode.checked ? "light" : "dark")
+        checked: Backend.colorSchemeName == "dark"
+        onClicked: Backend.changeColorScheme( darkMode.checked ? "light" : "dark")
 
         Layout.fillWidth: true
     }
diff --git a/internal/frontend/bridge-gui/qml/HelpView.qml b/internal/frontend/bridge-gui/qml/HelpView.qml
index 0b9d7095..5598bd7b 100644
--- a/internal/frontend/bridge-gui/qml/HelpView.qml
+++ b/internal/frontend/bridge-gui/qml/HelpView.qml
@@ -15,11 +15,11 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
 
-import Proton 4.0
+import Proton
 
 SettingsView {
     id: root
@@ -38,7 +38,7 @@ SettingsView {
         colorScheme: root.colorScheme
         text: qsTr("Installation and setup")
         actionText: qsTr("Go to help topics")
-        actionIcon: "./icons/ic-external-link.svg"
+        actionIcon: "/qml/icons/ic-external-link.svg"
         description: qsTr("Get help setting up your client with our instructions and FAQs.")
         type: SettingsItem.PrimaryButton
         onClicked: {Qt.openUrlExternally("https://protonmail.com/support/categories/bridge/")}
@@ -55,10 +55,13 @@ SettingsView {
         type: SettingsItem.Button
         onClicked: {
             checkUpdates.loading = true
-            root.backend.checkUpdates()
+            Backend.checkUpdates()
         }
 
-        Connections {target: root.backend; onCheckUpdatesFinished: checkUpdates.loading = false}
+        Connections {
+            target: Backend
+            function onCheckUpdatesFinished() { checkUpdates.loading = false }
+        }
 
         Layout.fillWidth: true
     }
@@ -70,7 +73,7 @@ SettingsView {
         actionText: qsTr("View logs")
         description: qsTr("Open and review logs to troubleshoot.")
         type: SettingsItem.Button
-        onClicked: Qt.openUrlExternally(root.backend.logsPath)
+        onClicked: Qt.openUrlExternally(Backend.logsPath)
 
         Layout.fillWidth: true
     }
@@ -83,7 +86,7 @@ SettingsView {
         description: qsTr("Something not working as expected? Let us know.")
         type: SettingsItem.Button
         onClicked: {
-            root.backend.updateCurrentMailClient()
+            Backend.updateCurrentMailClient()
             root.parent.showBugReport()
         }
 
@@ -106,11 +109,11 @@ SettingsView {
         horizontalAlignment: Text.AlignHCenter
 
         text: qsTr("Proton Mail Bridge v%1<br>© 2021 Proton AG<br>%2 %3<br>%4").
-        arg(root.backend.version).
-        arg(link(root.backend.licensePath, qsTr("License"))).
-        arg(link(root.backend.dependencyLicensesLink, qsTr("Dependencies"))).
-        arg(link(root.backend.releaseNotesLink, qsTr("Release notes")))
+        arg(Backend.version).
+        arg(link(Backend.licensePath, qsTr("License"))).
+        arg(link(Backend.dependencyLicensesLink, qsTr("Dependencies"))).
+        arg(link(Backend.releaseNotesLink, qsTr("Release notes")))
 
-        onLinkActivated: Qt.openUrlExternally(link)
+        onLinkActivated: function(link) { Qt.openUrlExternally(link) }
     }
 }
diff --git a/internal/frontend/bridge-gui/qml/KeychainSettings.qml b/internal/frontend/bridge-gui/qml/KeychainSettings.qml
index e9f3a824..c00a3518 100644
--- a/internal/frontend/bridge-gui/qml/KeychainSettings.qml
+++ b/internal/frontend/bridge-gui/qml/KeychainSettings.qml
@@ -15,19 +15,19 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.13
-import QtQuick.Controls.impl 2.13
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
+import QtQuick.Controls.impl
 
-import Proton 4.0
+import Proton
 
 SettingsView {
     id: root
 
     fillHeight: false
 
-    property bool _valuesChanged: keychainSelection.checkedButton && keychainSelection.checkedButton.text != root.backend.currentKeychain
+    property bool _valuesChanged: keychainSelection.checkedButton && keychainSelection.checkedButton.text != Backend.currentKeychain
 
     Label {
         colorScheme: root.colorScheme
@@ -51,7 +51,7 @@ SettingsView {
         ButtonGroup{ id: keychainSelection }
 
         Repeater {
-            model: root.backend.availableKeychain
+            model: Backend.availableKeychain
 
             RadioButton {
                 colorScheme: root.colorScheme
@@ -77,7 +77,7 @@ SettingsView {
             text: qsTr("Save and restart")
             enabled: root._valuesChanged
             onClicked: {
-                root.backend.changeKeychain(keychainSelection.checkedButton.text)
+                Backend.changeKeychain(keychainSelection.checkedButton.text)
             }
         }
 
@@ -89,9 +89,9 @@ SettingsView {
         }
 
         Connections {
-            target: root.backend
+            target: Backend
 
-            onChangeKeychainFinished: {
+            function onChangeKeychainFinished() {
                 submitButton.loading = false
                 root.back()
             }
@@ -105,7 +105,7 @@ SettingsView {
     function setDefaultValues(){
         for (var bi in keychainSelection.buttons){
             var button = keychainSelection.buttons[bi]
-            if (button.text == root.backend.currentKeychain) {
+            if (button.text == Backend.currentKeychain) {
                 button.checked = true
                 break;
             }
diff --git a/internal/frontend/bridge-gui/qml/LocalCacheSettings.qml b/internal/frontend/bridge-gui/qml/LocalCacheSettings.qml
index bf618342..1cae357b 100644
--- a/internal/frontend/bridge-gui/qml/LocalCacheSettings.qml
+++ b/internal/frontend/bridge-gui/qml/LocalCacheSettings.qml
@@ -15,13 +15,13 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.13
-import QtQuick.Controls.impl 2.13
-import QtQuick.Dialogs 1.1
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
+import QtQuick.Controls.impl
+import QtQuick.Dialogs
 
-import Proton 4.0
+import Proton
 
 SettingsView {
     id: root
@@ -64,7 +64,7 @@ SettingsView {
         colorScheme: root.colorScheme
         text: qsTr("Current cache location")
         actionText: qsTr("Change location")
-        description: root.backend.goos === "windows" ?
+        description: Backend.goos === "windows" ?
                          root._diskCachePath.toString().replace("file:///", "").replace(new RegExp("/", 'g'), "\\") + "\\" :
                          root._diskCachePath.toString().replace("file://", "") + "/"
         descriptionWrap: Text.WrapAnywhere
@@ -76,13 +76,12 @@ SettingsView {
 
         Layout.fillWidth: true
 
-        FileDialog {
+        FolderDialog {
             id: pathDialog
             title: qsTr("Select cache location")
-            folder: root._diskCachePath
+            currentFolder: root._diskCachePath
             onAccepted: root._diskCachePath = pathDialog.fileUrl
-            selectFolder: true
-        }
+       }
     }
 
     RowLayout {
@@ -93,8 +92,8 @@ SettingsView {
             colorScheme: root.colorScheme
             text: qsTr("Save and restart")
             enabled: (
-                root.backend.diskCachePath != root._diskCachePath ||
-                root.backend.isDiskCacheEnabled != root._diskCacheEnabled
+                Backend.diskCachePath != root._diskCachePath ||
+                Backend.isDiskCacheEnabled != root._diskCacheEnabled
             )
             onClicked: {
                 root.submit()
@@ -109,9 +108,9 @@ SettingsView {
         }
 
         Connections {
-            target: root.backend
+            target: Backend
 
-            onChangeLocalCacheFinished: {
+            function onChangeLocalCacheFinished() {
                 submitButton.loading = false
                 root.setDefaultValues()
             }
@@ -123,24 +122,24 @@ SettingsView {
     }
 
     function submit(){
-        if (!root._diskCacheEnabled && root.backend.isDiskCacheEnabled) {
+        if (!root._diskCacheEnabled && Backend.isDiskCacheEnabled) {
             root.notifications.askDisableLocalCache()
             return
         }
 
-        if (root._diskCacheEnabled && !root.backend.isDiskCacheEnabled) {
+        if (root._diskCacheEnabled && !Backend.isDiskCacheEnabled) {
             root.notifications.askEnableLocalCache(root._diskCachePath)
             return
         }
 
         // Not asking, only changing path
         submitButton.loading = true
-        root.backend.changeLocalCache(root.backend.isDiskCacheEnabled, root._diskCachePath)
+        Backend.changeLocalCache(Backend.isDiskCacheEnabled, root._diskCachePath)
     }
 
     function setDefaultValues(){
-        root._diskCacheEnabled = root.backend.isDiskCacheEnabled
-        root._diskCachePath = root.backend.diskCachePath
+        root._diskCacheEnabled = Backend.isDiskCacheEnabled
+        root._diskCachePath = Backend.diskCachePath
     }
 
     onVisibleChanged: {
diff --git a/internal/frontend/bridge-gui/qml/MainWindow.qml b/internal/frontend/bridge-gui/qml/MainWindow.qml
index 79cd2bd3..e614c881 100644
--- a/internal/frontend/bridge-gui/qml/MainWindow.qml
+++ b/internal/frontend/bridge-gui/qml/MainWindow.qml
@@ -15,15 +15,14 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQml 2.12
-import QtQuick 2.13
-import QtQuick.Window 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
+import QtQml
+import QtQuick
+import QtQuick.Window
+import QtQuick.Layouts
+import QtQuick.Controls
 
-import Proton 4.0
-import Notifications 1.0
-import CppBackend 1.0
+import Proton
+import Notifications
 
 import "tests"
 
@@ -40,8 +39,6 @@ ApplicationWindow {
 
     colorScheme: ProtonStyle.currentStyle
 
-
-    property var backend
     property var notifications
 
     // This is needed because on MacOS if first window shown is not transparent -
@@ -52,11 +49,11 @@ ApplicationWindow {
 
     // show Setup Guide on every new user
     Connections {
-        target: root.backend.users
+        target: Backend.users
 
-        onRowsInserted: {
+        function onRowsInserted(parent, first, last) {
             // considerring that users are added one-by-one
-            var user = root.backend.users.get(first)
+            var user = Backend.users.get(first)
 
             if (!user.loggedIn) {
                 return
@@ -69,9 +66,9 @@ ApplicationWindow {
             root.showSetup(user,user.addresses[0])
         }
 
-        onRowsAboutToBeRemoved: {
+        function onRowsAboutToBeRemoved(parent, first, last) {
             for (var i = first; i <= last; i++ ) {
-                var user = root.backend.users.get(i)
+                var user = Backend.users.get(i)
 
                 if (setupGuide.user === user) {
                     setupGuide.user = null
@@ -83,13 +80,13 @@ ApplicationWindow {
     }
 
     Connections {
-        target: root.backend
+        target: Backend
 
-        onShowMainWindow: {
+        function onShowMainWindow() {
             root.showAndRise()
         }
 
-        onLoginFinished: {
+        function onLoginFinished(index) {
             console.debug("Login finished", index)
         }
     }
@@ -102,11 +99,11 @@ ApplicationWindow {
         property bool _showSetup: false
         currentIndex: {
             // show welcome when there are no users or only one non-logged-in user is present
-            if (backend.users.count === 0) {
+            if (Backend.users.count === 0) {
                 return 1
             }
 
-            var u = backend.users.get(0)
+            var u = Backend.users.get(0)
 
             if (!u) {
                 console.trace()
@@ -114,7 +111,7 @@ ApplicationWindow {
                 return 1
             }
 
-            if (backend.users.count === 1 && u.loggedIn === false) {
+            if (Backend.users.count === 1 && u.loggedIn === false) {
                 return 1
             }
 
@@ -128,7 +125,6 @@ ApplicationWindow {
         ContentWrapper { // 0
             id: contentWrapper
             colorScheme: root.colorScheme
-            backend: root.backend
             notifications: root.notifications
 
             Layout.fillHeight: true
@@ -141,7 +137,6 @@ ApplicationWindow {
 
         WelcomeGuide { // 1
             colorScheme: root.colorScheme
-            backend: root.backend
 
             Layout.fillHeight: true
             Layout.fillWidth: true
@@ -150,7 +145,6 @@ ApplicationWindow {
         SetupGuide { // 2
             id: setupGuide
             colorScheme: root.colorScheme
-            backend: root.backend
 
             Layout.fillHeight: true
             Layout.fillWidth: true
@@ -160,8 +154,8 @@ ApplicationWindow {
             }
 
             onFinished: {
-                // TODO: Do not close window. Trigger backend to check that
-                // there is a successfully connected client. Then backend
+                // TODO: Do not close window. Trigger Backend to check that
+                // there is a successfully connected client. Then Backend
                 // should send another signal to close the setup guide.
                 root.showSetup(null,"")
             }
@@ -173,13 +167,11 @@ ApplicationWindow {
         colorScheme: root.colorScheme
         notifications: root.notifications
         mainWindow: root
-        backend: root.backend
     }
 
     SplashScreen {
         id: splashScreen
         colorScheme: root.colorScheme
-        backend: root.backend
     }
 
     function showLocalCacheSettings() { contentWrapper.showLocalCacheSettings() }
diff --git a/internal/frontend/bridge-gui/qml/NotificationDialog.qml b/internal/frontend/bridge-gui/qml/NotificationDialog.qml
index 7b73caa7..3af8f070 100644
--- a/internal/frontend/bridge-gui/qml/NotificationDialog.qml
+++ b/internal/frontend/bridge-gui/qml/NotificationDialog.qml
@@ -15,13 +15,13 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQml 2.12
-import QtQuick 2.12
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
+import QtQml
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
 
-import Proton 4.0
-import Notifications 1.0
+import Proton
+import Notifications
 
 Dialog {
     id: root
@@ -56,12 +56,12 @@ Dialog {
 
                 switch (root.notification.type) {
                     case Notification.NotificationType.Info:
-                    return "./icons/ic-info.svg"
+                    return "/qml/icons/ic-info.svg"
                     case Notification.NotificationType.Success:
-                    return "./icons/ic-success.svg"
+                    return "/qml/icons/ic-success.svg"
                     case Notification.NotificationType.Warning:
                     case Notification.NotificationType.Danger:
-                    return "./icons/ic-alert.svg"
+                    return "/qml/icons/ic-alert.svg"
                 }
             }
         }
@@ -84,7 +84,7 @@ Dialog {
             wrapMode: Text.WordWrap
             horizontalAlignment: Text.AlignHCenter
             type: Label.LabelType.Body
-            onLinkActivated: Qt.openUrlExternally(link)
+            onLinkActivated: function(link) { Qt.openUrlExternally(link) }
         }
 
         Item {
diff --git a/internal/frontend/bridge-gui/qml/NotificationPopups.qml b/internal/frontend/bridge-gui/qml/NotificationPopups.qml
index 211ce858..65f27b9d 100644
--- a/internal/frontend/bridge-gui/qml/NotificationPopups.qml
+++ b/internal/frontend/bridge-gui/qml/NotificationPopups.qml
@@ -15,17 +15,16 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQml 2.12
-import QtQuick 2.12
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
+import QtQml
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
 
-import Proton 4.0
-import Notifications 1.0
+import Proton
+import Notifications
 
 Item {
     id: root
-    property var backend
 
     property ColorScheme colorScheme
     property var notifications
@@ -55,8 +54,8 @@ Item {
             id:autoUpdate
             colorScheme: root.colorScheme
             text: qsTr("Update automatically in the future")
-            checked: root.backend.isAutomaticUpdateOn
-            onClicked: root.backend.toggleAutomaticUpdate(autoUpdate.checked)
+            checked: Backend.isAutomaticUpdateOn
+            onClicked: Backend.toggleAutomaticUpdate(autoUpdate.checked)
         }
     }
 
diff --git a/internal/frontend/bridge-gui/qml/Notifications/Notification.qml b/internal/frontend/bridge-gui/qml/Notifications/Notification.qml
index 6b2718b7..067f6bfb 100644
--- a/internal/frontend/bridge-gui/qml/Notifications/Notification.qml
+++ b/internal/frontend/bridge-gui/qml/Notifications/Notification.qml
@@ -15,8 +15,8 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQml 2.12
-import QtQuick.Controls 2.12
+import QtQml
+import QtQuick.Controls
 
 QtObject {
     id: root
diff --git a/internal/frontend/bridge-gui/qml/Notifications/NotificationFilter.qml b/internal/frontend/bridge-gui/qml/Notifications/NotificationFilter.qml
index 2477788e..bd6d94ad 100644
--- a/internal/frontend/bridge-gui/qml/Notifications/NotificationFilter.qml
+++ b/internal/frontend/bridge-gui/qml/Notifications/NotificationFilter.qml
@@ -15,8 +15,8 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQml 2.12
-import QtQml.Models 2.12
+import QtQml
+import QtQml.Models
 
 // contains notifications that satisfy black- and whitelist and are sorted in time-occurred order
 ListModel {
diff --git a/internal/frontend/bridge-gui/qml/Notifications/Notifications.qml b/internal/frontend/bridge-gui/qml/Notifications/Notifications.qml
index 32370fad..8f897239 100644
--- a/internal/frontend/bridge-gui/qml/Notifications/Notifications.qml
+++ b/internal/frontend/bridge-gui/qml/Notifications/Notifications.qml
@@ -15,16 +15,14 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQml 2.12
-import Qt.labs.platform 1.1
-import QtQuick.Controls 2.12
+import QtQml
+import Qt.labs.platform
+import QtQuick.Controls
 import ".."
 
 QtObject {
     id: root
 
-    property var backend
-
     property MainWindow frontendMain
     property StatusWindow frontendStatus
     property SystemTrayIcon frontendTray
@@ -89,12 +87,12 @@ QtObject {
         group: Notifications.Group.Connection
 
         Connections {
-            target: root.backend
+            target: Backend
 
-            onInternetOff: {
+            function onInternetOff() {
                 root.noInternet.active = true
             }
-            onInternetOn: {
+            function onInternetOn() {
                 root.noInternet.active = false
             }
         }
@@ -106,7 +104,7 @@ QtObject {
         description:  {
             var descr = qsTr("A new version of Proton Mail Bridge is available.")
             var text = qsTr("See what's changed.")
-            var link = root.backend.releaseNotesLink
+            var link = Backend.releaseNotesLink
             return `${descr} <a href="${link}">${text}</a>`
         }
         brief: qsTr("Update available.")
@@ -115,8 +113,8 @@ QtObject {
         group: Notifications.Group.Update | Notifications.Group.Dialogs
 
         Connections {
-            target: root.backend
-            onUpdateManualReady: {
+            target: Backend
+            function onUpdateManualReady(version) {
                 root.updateManualReady.data = { version: version }
                 root.updateManualReady.active = true
             }
@@ -127,7 +125,7 @@ QtObject {
                 text: qsTr("Install update")
 
                 onTriggered: {
-                    root.backend.installUpdate()
+                    Backend.installUpdate()
                     root.updateManualReady.active = false
                 }
             },
@@ -135,7 +133,7 @@ QtObject {
                 text: qsTr("Update manually")
 
                 onTriggered: {
-                    Qt.openUrlExternally(root.backend.landingPageLink)
+                    Qt.openUrlExternally(Backend.landingPageLink)
                     root.updateManualReady.active = false
                 }
             },
@@ -157,8 +155,8 @@ QtObject {
         group: Notifications.Group.Update
 
         Connections {
-            target: root.backend
-            onUpdateManualRestartNeeded: {
+            target: Backend
+            function onUpdateManualRestartNeeded() {
                 root.updateManualRestartNeeded.active = true
             }
         }
@@ -167,7 +165,7 @@ QtObject {
             text: qsTr("Restart Bridge")
 
             onTriggered: {
-                root.backend.restart()
+                Backend.restart()
                 root.updateManualRestartNeeded.active = false
             }
         }
@@ -182,8 +180,8 @@ QtObject {
         group: Notifications.Group.Update
 
         Connections {
-            target: root.backend
-            onUpdateManualError: {
+            target: Backend
+            function onUpdateManualError() {
                 root.updateManualError.active = true
             }
         }
@@ -193,7 +191,7 @@ QtObject {
                 text: qsTr("Update manually")
 
                 onTriggered: {
-                    Qt.openUrlExternally(root.backend.landingPageLink)
+                    Qt.openUrlExternally(Backend.landingPageLink)
                     root.updateManualError.active = false
                     root.backend.quit()
                 }
@@ -217,9 +215,9 @@ QtObject {
         group: Notifications.Group.Update | Notifications.Group.ForceUpdate | Notifications.Group.Dialogs
 
         Connections {
-            target: root.backend
+            target: Backend
 
-            onUpdateForce: {
+            function onUpdateForce(version) {
                 root.updateForce.data = { version: version }
                 root.updateForce.active = true
             }
@@ -230,7 +228,7 @@ QtObject {
                 text: qsTr("Install update")
 
                 onTriggered: {
-                    root.backend.installUpdate()
+                    Backend.installUpdate()
                     root.updateForce.active = false
                 }
             },
@@ -238,7 +236,7 @@ QtObject {
                 text: qsTr("Update manually")
 
                 onTriggered: {
-                    Qt.openUrlExternally(root.backend.landingPageLink)
+                    Qt.openUrlExternally(Backend.landingPageLink)
                     root.updateForce.active = false
                 }
             },
@@ -246,7 +244,7 @@ QtObject {
                 text: qsTr("Quit Bridge")
 
                 onTriggered: {
-                    root.backend.quit()
+                    Backend.quit()
                     root.updateForce.active = false
                 }
             }
@@ -262,9 +260,9 @@ QtObject {
         group: Notifications.Group.Update | Notifications.Group.Dialogs
 
         Connections {
-            target: root.backend
+            target: Backend
 
-            onUpdateForceError: {
+            function onUpdateForceError() {
                 root.updateForceError.active = true
             }
         }
@@ -274,7 +272,7 @@ QtObject {
                 text: qsTr("Update manually")
 
                 onTriggered: {
-                    Qt.openUrlExternally(root.backend.landingPageLink)
+                    Qt.openUrlExternally(Backend.landingPageLink)
                     root.updateForceError.active = false
                 }
             },
@@ -282,7 +280,7 @@ QtObject {
                 text: qsTr("Quit Bridge")
 
                 onTriggered: {
-                    root.backend.quit()
+                    Backend.quit()
                     root.updateForceError.active = false
                 }
             }
@@ -297,8 +295,8 @@ QtObject {
         group: Notifications.Group.Update
 
         Connections {
-            target: root.backend
-            onUpdateSilentRestartNeeded: {
+            target: Backend
+            function onUpdateSilentRestartNeeded() {
                 root.updateSilentRestartNeeded.active = true
             }
         }
@@ -307,7 +305,7 @@ QtObject {
             text: qsTr("Restart Bridge")
 
             onTriggered: {
-                root.backend.restart()
+                Backend.restart()
                 root.updateSilentRestartNeeded.active = false
             }
         }
@@ -321,8 +319,8 @@ QtObject {
         group: Notifications.Group.Update
 
         Connections {
-            target: root.backend
-            onUpdateSilentError: {
+            target: Backend
+            function onUpdateSilentError() {
                 root.updateSilentError.active = true
             }
         }
@@ -331,7 +329,7 @@ QtObject {
             text: qsTr("Update manually")
 
             onTriggered: {
-                Qt.openUrlExternally(root.backend.landingPageLink)
+                Qt.openUrlExternally(Backend.landingPageLink)
                 root.updateSilentError.active = false
             }
         }
@@ -345,8 +343,8 @@ QtObject {
         group: Notifications.Group.Update
 
         Connections {
-            target: root.backend
-            onUpdateIsLatestVersion: {
+            target: Backend
+            function onUpdateIsLatestVersion() {
                 root.updateIsLatestVersion.active = true
             }
         }
@@ -370,7 +368,7 @@ QtObject {
 
         Connections {
             target: root
-            onAskEnableBeta: {
+            function onAskEnableBeta() {
                 root.enableBeta.active = true
             }
         }
@@ -379,7 +377,7 @@ QtObject {
             Action {
                 text: qsTr("Enable")
                 onTriggered: {
-                    root.backend.toggleBeta(true)
+                    Backend.toggleBeta(true)
                     root.enableBeta.active = false
                 }
             },
@@ -402,8 +400,8 @@ QtObject {
         group: Notifications.Group.Configuration
 
         Connections {
-            target: root.backend
-            onLoginConnectionError: {
+            target: Backend
+            function onLoginConnectionError(errorMsg) {
                 root.loginConnectionError.active = true
             }
         }
@@ -426,8 +424,8 @@ QtObject {
         group: Notifications.Group.Configuration
 
         Connections {
-            target: root.backend
-            onLoginFreeUserError: {
+            target: Backend
+            function onLoginFreeUserError() {
                 root.onlyPaidUsers.active = true
             }
         }
@@ -450,8 +448,8 @@ QtObject {
         group: Notifications.Group.Configuration
 
         Connections {
-            target: root.backend
-            onLoginAlreadyLoggedIn: {
+            target: Backend
+            function onLoginAlreadyLoggedIn(index) {
                 root.alreadyLoggedIn.active = true
             }
         }
@@ -475,8 +473,8 @@ QtObject {
         group: Notifications.Group.Configuration
 
         Connections {
-            target: root.backend
-            onBugReportSendSuccess: {
+            target: Backend
+            function onBugReportSendSuccess() {
                 root.bugReportSendSuccess.active = true
             }
         }
@@ -499,8 +497,8 @@ QtObject {
         group: Notifications.Group.Configuration
 
         Connections {
-            target: root.backend
-            onBugReportSendError: {
+            target: Backend
+            function onBugReportSendError() {
                 root.bugReportSendError.active = true
             }
         }
@@ -523,8 +521,8 @@ QtObject {
         group: Notifications.Group.Configuration | Notifications.Group.Dialogs
 
         Connections {
-            target: root.backend
-            onCacheUnavailable: {
+            target: Backend
+            function onCacheUnavailable() {
                 root.cacheUnavailable.active = true
             }
         }
@@ -533,7 +531,7 @@ QtObject {
             Action {
                 text: qsTr("Quit Bridge")
                 onTriggered: {
-                    root.backend.quit()
+                    Backend.quit()
                     root.cacheUnavailable.active = false
                 }
             },
@@ -556,8 +554,8 @@ QtObject {
         group: Notifications.Group.Configuration | Notifications.Group.Dialogs
 
         Connections {
-            target: root.backend
-            onCacheCantMove: {
+            target: Backend
+            function onCacheCantMove() {
                 root.cacheCantMove.active = true
             }
         }
@@ -587,8 +585,8 @@ QtObject {
         group: Notifications.Group.Configuration
 
         Connections {
-            target: root.backend
-            onCacheLocationChangeSuccess: {
+            target: Backend
+            function onCacheLocationChangeSuccess() {
                 console.log("notify location changed succesfully")
                 root.cacheLocationChangeSuccess.active = true
             }
@@ -630,8 +628,8 @@ QtObject {
         group: Notifications.Group.Configuration | Notifications.Group.Dialogs
 
         Connections {
-            target: root.backend
-            onDiskFull: {
+            target: Backend
+            function onDiskFull() {
                 root.diskFull.active = true
             }
         }
@@ -640,7 +638,7 @@ QtObject {
             Action {
                 text: qsTr("Quit Bridge")
                 onTriggered: {
-                    root.backend.quit()
+                    Backend.quit()
                     root.diskFull.active = false
                 }
             },
@@ -658,7 +656,7 @@ QtObject {
         title: qsTr("Enable split mode?")
         brief: title
         description: qsTr("Changing between split and combined address mode will require you to delete your account(s) from your email client and begin the setup process from scratch.")
-        icon: "./icons/ic-question-circle.svg"
+        icon: "/qml/icons/ic-question-circle.svg"
         type: Notification.NotificationType.Warning
         group: Notifications.Group.Configuration | Notifications.Group.Dialogs
 
@@ -666,7 +664,7 @@ QtObject {
 
         Connections {
             target: root
-            onAskEnableSplitMode: {
+            function onAskEnableSplitMode(user) {
                 root.enableSplitMode.user = user
                 root.enableSplitMode.active = true
             }
@@ -674,7 +672,7 @@ QtObject {
 
         Connections {
             target: (root && root.enableSplitMode && root.enableSplitMode.user ) ? root.enableSplitMode.user : null
-            onToggleSplitModeFinished: {
+            function onToggleSplitModeFinished() {
                 root.enableSplitMode.active = false
 
                 enableSplitMode_enable.loading = false
@@ -706,20 +704,20 @@ QtObject {
         title: qsTr("Disable local cache?")
         brief: title
         description: qsTr("This action will clear your local cache, including locally stored messages. Bridge will restart.")
-        icon: "./icons/ic-question-circle.svg"
+        icon: "/qml/icons/ic-question-circle.svg"
         type: Notification.NotificationType.Warning
         group: Notifications.Group.Configuration | Notifications.Group.Dialogs
 
         Connections {
             target: root
-            onAskDisableLocalCache: {
+            function onAskDisableLocalCache() {
                 root.disableLocalCache.active = true
             }
         }
 
         Connections {
-            target: root.backend
-            onChangeLocalCacheFinished: {
+            target: Backend
+            function onChangeLocalCacheFinished() {
                 root.disableLocalCache.active = false
 
                 disableLocalCache_disable.loading = false
@@ -741,7 +739,7 @@ QtObject {
                 onTriggered: {
                     disableLocalCache_disable.loading = true
                     disableLocalCache_cancel.enabled = false
-                    root.backend.changeLocalCache(false, root.backend.diskCachePath)
+                    Backend.changeLocalCache(false, Backend.diskCachePath)
                 }
             }
         ]
@@ -751,7 +749,7 @@ QtObject {
         title: qsTr("Enable local cache")
         brief: title
         description: qsTr("Bridge will restart.")
-        icon: "./icons/ic-question-circle.svg"
+        icon: "/qml/icons/ic-question-circle.svg"
         type: Notification.NotificationType.Warning
         group: Notifications.Group.Configuration | Notifications.Group.Dialogs
 
@@ -759,15 +757,15 @@ QtObject {
 
         Connections {
             target: root
-            onAskEnableLocalCache: {
+            function onAskEnableLocalCache(path) {
                 root.enableLocalCache.active = true
                 root.enableLocalCache.path = path
             }
         }
 
         Connections {
-            target: root.backend
-            onChangeLocalCacheFinished: {
+            target: Backend
+            function onChangeLocalCacheFinished() {
                 root.enableLocalCache.active = false
 
                 enableLocalCache_enable.loading = false
@@ -782,7 +780,7 @@ QtObject {
                 onTriggered: {
                     enableLocalCache_enable.loading = true
                     enableLocalCache_cancel.enabled = false
-                    root.backend.changeLocalCache(true, root.enableLocalCache.path)
+                    Backend.changeLocalCache(true, root.enableLocalCache.path)
                 }
             },
             Action {
@@ -807,14 +805,14 @@ QtObject {
 
         Connections {
             target: root
-            onAskResetBridge: {
+            function onAskResetBridge() {
                 root.resetBridge.active = true
             }
         }
 
         Connections {
-            target: root.backend
-            onResetFinished: {
+            target: Backend
+            function onResetFinished() {
                 root.resetBridge.active = false
 
                 resetBridge_reset.loading = false
@@ -836,7 +834,7 @@ QtObject {
                 onTriggered: {
                     resetBridge_reset.loading = true
                     resetBridge_cancel.enabled = false
-                    root.backend.triggerReset()
+                    Backend.triggerReset()
                 }
             }
         ]
@@ -895,7 +893,7 @@ QtObject {
 
         Connections {
             target: root
-            onAskDeleteAccount: {
+            function onAskDeleteAccount(user) {
                 root.deleteAccount.user = user
                 root.deleteAccount.active = true
             }
@@ -929,9 +927,9 @@ QtObject {
         group: Notifications.Group.Dialogs | Notifications.Group.Configuration
 
         Connections {
-            target: root.backend
+            target: Backend
 
-            onNotifyHasNoKeychain: {
+            function onNotifyHasNoKeychain() {
                 root.noKeychain.active = true
             }
         }
@@ -941,14 +939,14 @@ QtObject {
                 text: qsTr("Quit Bridge")
 
                 onTriggered: {
-                    root.backend.quit()
+                    Backend.quit()
                 }
             },
             Action {
                 text: qsTr("Restart Bridge")
 
                 onTriggered: {
-                    root.backend.restart()
+                    Backend.restart()
                 }
             }
         ]
@@ -966,9 +964,9 @@ QtObject {
 
 
         Connections {
-            target: root.backend
+            target: Backend
 
-            onNotifyRebuildKeychain: {
+            function onNotifyRebuildKeychain() {
                 console.log("notifications")
                 root.rebuildKeychain.active = true
             }
@@ -980,7 +978,7 @@ QtObject {
 
                 onTriggered: {
                     Qt.openUrlExternally(root.rebuildKeychain.supportLink)
-                    root.backend.quit()
+                    Backend.quit()
                 }
             }
         ]
@@ -995,14 +993,14 @@ QtObject {
         group: Notifications.Group.Configuration
 
         Connections {
-            target: root.backend
+            target: Backend
 
-            onAddressChanged: {
+            function onAddressChanged(address) {
                 root.addressChanged.description = qsTr("The address list for your account %1 has changed. You might need to reconfigure your email client.").arg(address)
                 root.addressChanged.active = true
             }
 
-            onAddressChangedLogout: {
+            function onAddressChangedLogout(address) {
                 root.addressChanged.description = qsTr("The address list for your account %1 has changed. You have to reconfigure your email client.").arg(address)
                 root.addressChanged.active = true
             }
diff --git a/internal/frontend/bridge-gui/qml/PortSettings.qml b/internal/frontend/bridge-gui/qml/PortSettings.qml
index 943e6b0c..05a6632f 100644
--- a/internal/frontend/bridge-gui/qml/PortSettings.qml
+++ b/internal/frontend/bridge-gui/qml/PortSettings.qml
@@ -15,12 +15,12 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.13
-import QtQuick.Controls.impl 2.13
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
+import QtQuick.Controls.impl
 
-import Proton 4.0
+import Proton
 
 SettingsView {
     id: root
@@ -28,8 +28,8 @@ SettingsView {
     fillHeight: false
 
     property bool _valuesChanged: (
-        imapField.text*1 !== root.backend.portIMAP ||
-        smtpField.text*1 !== root.backend.portSMTP
+        imapField.text*1 !== Backend.portIMAP ||
+        smtpField.text*1 !== Backend.portSMTP
     )
 
     Label {
@@ -107,7 +107,7 @@ SettingsView {
                     return
                 }
 
-                root.backend.changePorts(imapField.text, smtpField.text)
+                Backend.changePorts(imapField.text, smtpField.text)
             }
         }
 
@@ -119,9 +119,11 @@ SettingsView {
         }
 
         Connections {
-            target: root.backend
+            target: Backend
 
-            onChangePortFinished: submitButton.loading = false
+            function onChangePortFinished() {
+                submitButton.loading = false
+            }
         }
     }
 
@@ -144,9 +146,9 @@ SettingsView {
 
     function isPortFree(field) {
         var num = field.text*1
-        if (num === root.backend.portIMAP) return true
-        if (num === root.backend.portSMTP) return true
-        if (!root.backend.isPortFree(num)) {
+        if (num === Backend.portIMAP) return true
+        if (num === Backend.portSMTP) return true
+        if (!Backend.isPortFree(num)) {
             field.error = true
             field.errorString = qsTr("Port occupied")
             return false
@@ -156,8 +158,8 @@ SettingsView {
     }
 
     function setDefaultValues(){
-        imapField.text = backend.portIMAP
-        smtpField.text = backend.portSMTP
+        imapField.text = Backend.portIMAP
+        smtpField.text = Backend.portSMTP
     }
 
     Component.onCompleted: root.setDefaultValues()
diff --git a/internal/frontend/bridge-gui/qml/Proton/Action.qml b/internal/frontend/bridge-gui/qml/Proton/Action.qml
index aac7202d..690b131d 100644
--- a/internal/frontend/bridge-gui/qml/Proton/Action.qml
+++ b/internal/frontend/bridge-gui/qml/Proton/Action.qml
@@ -15,8 +15,8 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.12
-import QtQuick.Templates 2.12 as T
+import QtQuick
+import QtQuick.Templates as T
 
 T.Action {
     property bool loading
diff --git a/internal/frontend/bridge-gui/qml/Proton/ApplicationWindow.qml b/internal/frontend/bridge-gui/qml/Proton/ApplicationWindow.qml
index 9b72dfe1..604c8eab 100644
--- a/internal/frontend/bridge-gui/qml/Proton/ApplicationWindow.qml
+++ b/internal/frontend/bridge-gui/qml/Proton/ApplicationWindow.qml
@@ -15,12 +15,12 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQml 2.12
-import QtQuick 2.12
-import QtQuick.Window 2.12
-import QtQuick.Controls 2.12
-import QtQuick.Controls.impl 2.12
-import QtQuick.Templates 2.12 as T
+import QtQml
+import QtQuick
+import QtQuick.Window
+import QtQuick.Controls
+import QtQuick.Controls.impl
+import QtQuick.Templates as T
 
 T.ApplicationWindow {
     id: root
@@ -46,7 +46,7 @@ T.ApplicationWindow {
             return data(index(row, 0), Qt.DisplayRole)
         }
 
-        onRowsInserted: {
+        onRowsInserted: function(parent, first, last) {
             for (var i = first; i <= last; i++) {
                 var obj = popups.get(i)
                 obj.onShouldShowChanged.connect( root.processPopups )
@@ -55,7 +55,7 @@ T.ApplicationWindow {
             processPopups()
         }
 
-        onRowsAboutToBeRemoved: {
+        onRowsAboutToBeRemoved: function (parent, first, last) {
             for (var i = first; i <= last; i++ ) {
                 var obj = popups.get(i)
                 obj.onShouldShowChanged.disconnect( root.processPopups )
@@ -112,7 +112,7 @@ T.ApplicationWindow {
     Connections {
         target: root.popupVisible
 
-        onVisibleChanged: {
+        function onVisibleChanged() {
             if (root.popupVisible.visible) {
                 return
             }
@@ -124,11 +124,11 @@ T.ApplicationWindow {
 
     color: root.colorScheme.background_norm
 
-    overlay.modal: Rectangle {
+    Overlay.modal: Rectangle {
         color: root.colorScheme.backdrop_norm
     }
 
-    overlay.modeless: Rectangle {
+    Overlay.modeless: Rectangle {
         color: "transparent"
     }
 }
diff --git a/internal/frontend/bridge-gui/qml/Proton/Button.qml b/internal/frontend/bridge-gui/qml/Proton/Button.qml
index a521ab40..6f7a23d8 100644
--- a/internal/frontend/bridge-gui/qml/Proton/Button.qml
+++ b/internal/frontend/bridge-gui/qml/Proton/Button.qml
@@ -15,12 +15,11 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.12
-import QtQuick.Controls 2.12
-import QtQuick.Controls.impl 2.12
-import QtQuick.Templates 2.12 as T
-import QtQuick.Layouts 1.12
-
+import QtQuick
+import QtQuick.Controls
+import QtQuick.Controls.impl
+import QtQuick.Templates as T
+import QtQuick.Layouts
 import "." as Proton
 
 T.Button {
@@ -129,7 +128,7 @@ T.Button {
             sourceSize.height: control.icon.height
 
             color: control.icon.color
-            source: control.loading ? "../icons/Loader_16.svg" : control.icon.source
+            source: control.loading ? "/qml/icons/Loader_16.svg" : control.icon.source
             visible: control.loading || control.icon.source
 
             RotationAnimation {
@@ -147,7 +146,7 @@ T.Button {
     background: Rectangle {
         implicitWidth: 36
         implicitHeight: 36
-        radius: Style.button_radius
+        radius: ProtonStyle.button_radius
         visible: true
         color: {
             if (!isIcon) {
diff --git a/internal/frontend/bridge-gui/qml/Proton/CheckBox.qml b/internal/frontend/bridge-gui/qml/Proton/CheckBox.qml
index 2390ffa2..66262a54 100644
--- a/internal/frontend/bridge-gui/qml/Proton/CheckBox.qml
+++ b/internal/frontend/bridge-gui/qml/Proton/CheckBox.qml
@@ -15,10 +15,10 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.12
-import QtQuick.Controls 2.12
-import QtQuick.Controls.impl 2.12
-import QtQuick.Templates 2.12 as T
+import QtQuick
+import QtQuick.Controls
+import QtQuick.Controls.impl
+import QtQuick.Templates as T
 
 T.CheckBox {
     property ColorScheme colorScheme
@@ -39,7 +39,7 @@ T.CheckBox {
     indicator: Rectangle {
         implicitWidth: 20
         implicitHeight: 20
-        radius: Style.checkbox_radius
+        radius: ProtonStyle.checkbox_radius
 
         x: text ? (control.mirrored ? control.width - width - control.rightPadding : control.leftPadding) : control.leftPadding + (control.availableWidth - width) / 2
         y: control.topPadding + (control.availableHeight - height) / 2
@@ -90,7 +90,7 @@ T.CheckBox {
             sourceSize.width: parent.width - 4
             sourceSize.height: parent.height - 4
             color: "#FFFFFF"
-            source: "../icons/ic-check.svg"
+            source: "/qml/icons/ic-check.svg"
             visible: control.checkState === Qt.Checked
         }
 
@@ -124,11 +124,11 @@ T.CheckBox {
             return control.colorScheme.text_norm
         }
 
-        font.family: Style.font_family
-        font.weight: Style.fontWeight_400
-        font.pixelSize: Style.body_font_size
-        lineHeight: Style.body_line_height
+        font.family: ProtonStyle.font_family
+        font.weight: ProtonStyle.fontWeight_400
+        font.pixelSize: ProtonStyle.body_font_size
+        lineHeight: ProtonStyle.body_line_height
         lineHeightMode: Text.FixedHeight
-        font.letterSpacing: Style.body_letter_spacing
+        font.letterSpacing: ProtonStyle.body_letter_spacing
     }
 }
diff --git a/internal/frontend/bridge-gui/qml/Proton/ColorScheme.qml b/internal/frontend/bridge-gui/qml/Proton/ColorScheme.qml
index c29b2708..ed55b23d 100644
--- a/internal/frontend/bridge-gui/qml/Proton/ColorScheme.qml
+++ b/internal/frontend/bridge-gui/qml/Proton/ColorScheme.qml
@@ -15,7 +15,7 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQml 2.13
+import QtQml
 
 QtObject {
     // should be a pointer to ColorScheme object
diff --git a/internal/frontend/bridge-gui/qml/Proton/ComboBox.qml b/internal/frontend/bridge-gui/qml/Proton/ComboBox.qml
index f0dc5285..728458cf 100644
--- a/internal/frontend/bridge-gui/qml/Proton/ComboBox.qml
+++ b/internal/frontend/bridge-gui/qml/Proton/ComboBox.qml
@@ -15,11 +15,11 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.12
-import QtQuick.Window 2.12
-import QtQuick.Controls 2.12
-import QtQuick.Controls.impl 2.12
-import QtQuick.Templates 2.12 as T
+import QtQuick
+import QtQuick.Window
+import QtQuick.Controls
+import QtQuick.Controls.impl
+import QtQuick.Templates as T
 
 T.ComboBox {
     id: root
@@ -40,10 +40,10 @@ T.ComboBox {
 
     spacing: 8
 
-    font.family: Style.font_family
-    font.weight: Style.fontWeight_400
-    font.pixelSize: Style.body_font_size
-    font.letterSpacing: Style.body_letter_spacing
+    font.family: ProtonStyle.font_family
+    font.weight: ProtonStyle.fontWeight_400
+    font.pixelSize: ProtonStyle.body_font_size
+    font.letterSpacing: ProtonStyle.body_letter_spacing
 
     contentItem: T.TextField {
         padding: 5
@@ -64,7 +64,7 @@ T.ComboBox {
         placeholderTextColor: root.enabled ? root.colorScheme.text_hint : root.colorScheme.text_disabled
 
         background: Rectangle {
-            radius: Style.context_item_radius
+            radius: ProtonStyle.context_item_radius
             visible: root.enabled && root.editable && !root.flat
             border.color: {
                 if (root.activeFocus) {
@@ -85,7 +85,7 @@ T.ComboBox {
     background: Rectangle {
         implicitWidth: 140
         implicitHeight: 36
-        radius: Style.context_item_radius
+        radius: ProtonStyle.context_item_radius
         color: {
             if (root.down) {
                 return root.colorScheme.interaction_default_active
@@ -110,7 +110,7 @@ T.ComboBox {
         x: root.mirrored ? 12 : root.width - width - 12
         y: root.topPadding + (root.availableHeight - height) / 2
         color: root.enabled ? root.colorScheme.text_norm : root.colorScheme.text_disabled
-        source: popup.visible ? "../icons/ic-chevron-up.svg" : "../icons/ic-chevron-down.svg"
+        source: popup.visible ? "/qml/icons/ic-chevron-up.svg" : "/qml/icons/ic-chevron-down.svg"
 
         sourceSize.width: 16
         sourceSize.height: 16
@@ -142,7 +142,7 @@ T.ComboBox {
         palette.highlightedText: selected ? root.colorScheme.text_invert : root.colorScheme.text_norm
 
         background: PaddedRectangle {
-            radius: Style.context_item_radius
+            radius: ProtonStyle.context_item_radius
             color: {
                 if (parent.down) {
                     return root.colorScheme.interaction_default_active
@@ -187,7 +187,7 @@ T.ComboBox {
 
         background: Rectangle {
             color: root.colorScheme.background_norm
-            radius: Style.dialog_radius
+            radius: ProtonStyle.dialog_radius
             border.color: root.colorScheme.border_weak
             border.width: 1
         }
diff --git a/internal/frontend/bridge-gui/qml/Proton/Dialog.qml b/internal/frontend/bridge-gui/qml/Proton/Dialog.qml
index e8171561..48ffeb3b 100644
--- a/internal/frontend/bridge-gui/qml/Proton/Dialog.qml
+++ b/internal/frontend/bridge-gui/qml/Proton/Dialog.qml
@@ -15,11 +15,11 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQml 2.12
-import QtQuick 2.12
-import QtQuick.Templates 2.12 as T
-import QtQuick.Controls 2.12
-import QtQuick.Controls.impl 2.12
+import QtQml
+import QtQuick
+import QtQuick.Templates as T
+import QtQuick.Controls
+import QtQuick.Controls.impl
 
 T.Dialog {
     id: root
@@ -65,7 +65,7 @@ T.Dialog {
 
     background: Rectangle {
         color: root.colorScheme.background_norm
-        radius: Style.dialog_radius
+        radius: ProtonStyle.dialog_radius
     }
 
     // TODO: Add DropShadow here
diff --git a/internal/frontend/bridge-gui/qml/Proton/Label.qml b/internal/frontend/bridge-gui/qml/Proton/Label.qml
index 4099149c..a9130a98 100644
--- a/internal/frontend/bridge-gui/qml/Proton/Label.qml
+++ b/internal/frontend/bridge-gui/qml/Proton/Label.qml
@@ -15,10 +15,10 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Controls 2.12
-import QtQuick.Controls.impl 2.12
-import QtQuick.Templates 2.12 as T
+import QtQuick
+import QtQuick.Controls
+import QtQuick.Controls.impl
+import QtQuick.Templates as T
 
 import "." as Proton
 
@@ -53,67 +53,67 @@ T.Label {
     linkColor: root.colorScheme.interaction_norm
     palette.link: linkColor
 
-    font.family: Style.font_family
+    font.family: ProtonStyle.font_family
     lineHeightMode: Text.FixedHeight
 
     font.weight: {
         switch (root.type) {
         case Proton.Label.LabelType.Heading:
-            return Style.fontWeight_700
+            return ProtonStyle.fontWeight_700
         case Proton.Label.LabelType.Title:
-            return Style.fontWeight_700
+            return ProtonStyle.fontWeight_700
         case Proton.Label.LabelType.Lead:
-            return Style.fontWeight_400
+            return ProtonStyle.fontWeight_400
         case Proton.Label.LabelType.Body:
-            return Style.fontWeight_400
+            return ProtonStyle.fontWeight_400
         case Proton.Label.LabelType.Body_semibold:
-            return Style.fontWeight_600
+            return ProtonStyle.fontWeight_600
         case Proton.Label.LabelType.Body_bold:
-            return Style.fontWeight_700
+            return ProtonStyle.fontWeight_700
         case Proton.Label.LabelType.Caption:
-            return Style.fontWeight_400
+            return ProtonStyle.fontWeight_400
         case Proton.Label.LabelType.Caption_semibold:
-            return Style.fontWeight_600
+            return ProtonStyle.fontWeight_600
         case Proton.Label.LabelType.Caption_bold:
-            return Style.fontWeight_700
+            return ProtonStyle.fontWeight_700
         }
     }
 
     font.pixelSize: {
         switch (root.type) {
         case Proton.Label.LabelType.Heading:
-            return Style.heading_font_size
+            return ProtonStyle.heading_font_size
         case Proton.Label.LabelType.Title:
-            return Style.title_font_size
+            return ProtonStyle.title_font_size
         case Proton.Label.LabelType.Lead:
-            return Style.lead_font_size
+            return ProtonStyle.lead_font_size
         case Proton.Label.LabelType.Body:
         case Proton.Label.LabelType.Body_semibold:
         case Proton.Label.LabelType.Body_bold:
-            return Style.body_font_size
+            return ProtonStyle.body_font_size
         case Proton.Label.LabelType.Caption:
         case Proton.Label.LabelType.Caption_semibold:
         case Proton.Label.LabelType.Caption_bold:
-            return Style.caption_font_size
+            return ProtonStyle.caption_font_size
         }
     }
 
     lineHeight: {
         switch (root.type) {
         case Proton.Label.LabelType.Heading:
-            return Style.heading_line_height
+            return ProtonStyle.heading_line_height
         case Proton.Label.LabelType.Title:
-            return Style.title_line_height
+            return ProtonStyle.title_line_height
         case Proton.Label.LabelType.Lead:
-            return Style.lead_line_height
+            return ProtonStyle.lead_line_height
         case Proton.Label.LabelType.Body:
         case Proton.Label.LabelType.Body_semibold:
         case Proton.Label.LabelType.Body_bold:
-            return Style.body_line_height
+            return ProtonStyle.body_line_height
         case Proton.Label.LabelType.Caption:
         case Proton.Label.LabelType.Caption_semibold:
         case Proton.Label.LabelType.Caption_bold:
-            return Style.caption_line_height
+            return ProtonStyle.caption_line_height
         }
     }
 
@@ -126,11 +126,11 @@ T.Label {
         case Proton.Label.LabelType.Body:
         case Proton.Label.LabelType.Body_semibold:
         case Proton.Label.LabelType.Body_bold:
-            return Style.body_letter_spacing
+            return ProtonStyle.body_letter_spacing
         case Proton.Label.LabelType.Caption:
         case Proton.Label.LabelType.Caption_semibold:
         case Proton.Label.LabelType.Caption_bold:
-            return Style.caption_letter_spacing
+            return ProtonStyle.caption_letter_spacing
         }
     }
 
diff --git a/internal/frontend/bridge-gui/qml/Proton/Menu.qml b/internal/frontend/bridge-gui/qml/Proton/Menu.qml
index a444f453..ca110114 100644
--- a/internal/frontend/bridge-gui/qml/Proton/Menu.qml
+++ b/internal/frontend/bridge-gui/qml/Proton/Menu.qml
@@ -15,11 +15,11 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.12
-import QtQuick.Controls 2.12
-import QtQuick.Controls.impl 2.12
-import QtQuick.Templates 2.12 as T
-import QtQuick.Window 2.12
+import QtQuick
+import QtQuick.Controls
+import QtQuick.Controls.impl
+import QtQuick.Templates as T
+import QtQuick.Window
 import "."
 
 T.Menu {
@@ -67,6 +67,6 @@ T.Menu {
         color: colorScheme.background_norm
         border.width: 1
         border.color: colorScheme.border_weak
-        radius: Style.account_row_radius
+        radius: ProtonStyle.account_row_radius
     }
 }
diff --git a/internal/frontend/bridge-gui/qml/Proton/MenuItem.qml b/internal/frontend/bridge-gui/qml/Proton/MenuItem.qml
index 3307734d..39d91169 100644
--- a/internal/frontend/bridge-gui/qml/Proton/MenuItem.qml
+++ b/internal/frontend/bridge-gui/qml/Proton/MenuItem.qml
@@ -15,10 +15,10 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.12
-import QtQuick.Controls 2.12
-import QtQuick.Controls.impl 2.12
-import QtQuick.Templates 2.12 as T
+import QtQuick
+import QtQuick.Controls
+import QtQuick.Controls.impl
+import QtQuick.Templates as T
 import "."
 
 T.MenuItem {
@@ -39,10 +39,10 @@ T.MenuItem {
     icon.height: 24
     icon.color: control.enabled ? control.colorScheme.text_norm : control.colorScheme.text_disabled
 
-    font.family: Style.font_family
-    font.weight: Style.fontWeight_400
-    font.pixelSize: Style.body_font_size
-    font.letterSpacing: Style.body_letter_spacing
+    font.family: ProtonStyle.font_family
+    font.weight: ProtonStyle.fontWeight_400
+    font.pixelSize: ProtonStyle.body_font_size
+    font.letterSpacing: ProtonStyle.body_letter_spacing
 
     contentItem: IconLabel {
         id: iconLabel
@@ -66,7 +66,7 @@ T.MenuItem {
     background: Rectangle {
         implicitWidth: 164
         implicitHeight: 36
-        radius: Style.button_radius
+        radius: ProtonStyle.button_radius
         color: control.down ? control.colorScheme.interaction_default_active : control.highlighted ? control.colorScheme.interaction_default_hover : control.colorScheme.interaction_default
     }
 }
diff --git a/internal/frontend/bridge-gui/qml/Proton/Popup.qml b/internal/frontend/bridge-gui/qml/Proton/Popup.qml
index 57770590..33021db9 100644
--- a/internal/frontend/bridge-gui/qml/Proton/Popup.qml
+++ b/internal/frontend/bridge-gui/qml/Proton/Popup.qml
@@ -15,11 +15,11 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQml 2.12
-import QtQuick 2.12
-import QtQuick.Controls 2.12
-import QtQuick.Controls.impl 2.12
-import QtQuick.Templates 2.12 as T
+import QtQml
+import QtQuick
+import QtQuick.Controls
+import QtQuick.Controls.impl
+import QtQuick.Templates as T
 
 T.Popup {
     id: root
diff --git a/internal/frontend/bridge-gui/qml/Proton/RadioButton.qml b/internal/frontend/bridge-gui/qml/Proton/RadioButton.qml
index f10ee4da..46661969 100644
--- a/internal/frontend/bridge-gui/qml/Proton/RadioButton.qml
+++ b/internal/frontend/bridge-gui/qml/Proton/RadioButton.qml
@@ -15,10 +15,10 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.12
-import QtQuick.Controls 2.12
-import QtQuick.Controls.impl 2.12
-import QtQuick.Templates 2.12 as T
+import QtQuick
+import QtQuick.Controls
+import QtQuick.Controls.impl
+import QtQuick.Templates as T
 
 T.RadioButton {
     property ColorScheme colorScheme
@@ -105,11 +105,11 @@ T.RadioButton {
             return control.colorScheme.text_norm
         }
 
-        font.family: Style.font_family
-        font.weight: Style.fontWeight_400
-        font.pixelSize: Style.body_font_size
-        lineHeight: Style.body_line_height
+        font.family: ProtonStyle.font_family
+        font.weight: ProtonStyle.fontWeight_400
+        font.pixelSize: ProtonStyle.body_font_size
+        lineHeight: ProtonStyle.body_line_height
         lineHeightMode: Text.FixedHeight
-        font.letterSpacing: Style.body_letter_spacing
+        font.letterSpacing: ProtonStyle.body_letter_spacing
     }
 }
diff --git a/internal/frontend/bridge-gui/qml/Proton/Style.qml b/internal/frontend/bridge-gui/qml/Proton/Style.qml
index f5ea8fe7..1c8e96cb 100644
--- a/internal/frontend/bridge-gui/qml/Proton/Style.qml
+++ b/internal/frontend/bridge-gui/qml/Proton/Style.qml
@@ -16,8 +16,8 @@
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
 pragma Singleton
-import QtQml 2.13
-import QtQuick 2.12
+import QtQml
+import QtQuick
 
 import "./"
 
@@ -105,8 +105,8 @@ QtObject {
         backdrop_norm: Qt.rgba(12./255., 12./255., 20./255., 0.32)
 
         // Images
-        welcome_img: "icons/img-welcome.png"
-        logo_img: "icons/product_logos.svg"
+        welcome_img: "/qml/icons/img-welcome.png"
+        logo_img: "/qml/icons/product_logos.svg"
     }
 
     property ColorScheme lightProminentStyle: ColorScheme {
@@ -180,8 +180,8 @@ QtObject {
         backdrop_norm: Qt.rgba(0,0,0, 0.32)
 
         // Images
-        welcome_img: "icons/img-welcome-dark.png"
-        logo_img:    "icons/product_logos_dark.svg"
+        welcome_img: "/qml/icons/img-welcome-dark.png"
+        logo_img:    "/qml/icons/product_logos_dark.svg"
     }
 
     property ColorScheme darkStyle: ColorScheme {
@@ -255,8 +255,8 @@ QtObject {
         backdrop_norm: Qt.rgba(0,0,0,0.32)
 
         // Images
-        welcome_img: "icons/img-welcome-dark.png"
-        logo_img:    "icons/product_logos_dark.svg"
+        welcome_img: "/qml/icons/img-welcome-dark.png"
+        logo_img:    "/qml/icons/product_logos_dark.svg"
     }
 
     property ColorScheme darkProminentStyle: ColorScheme {
@@ -330,8 +330,8 @@ QtObject {
         backdrop_norm: Qt.rgba(0,0,0,0.32)
 
         // Images
-        welcome_img: "icons/img-welcome-dark.png"
-        logo_img:    "icons/product_logos_dark.svg"
+        welcome_img: "/qml/icons/img-welcome-dark.png"
+        logo_img:    "/qml/icons/product_logos_dark.svg"
     }
 
     property ColorScheme currentStyle: lightStyle
@@ -341,7 +341,7 @@ QtObject {
             case "windows":
             return "Segoe UI"
             case "osx":
-            return "SF Pro Display"
+            return ".AppleSystemUIFont" // should be SF Pro for the foreseeable future. Using "SF Pro Display" direcly here is not allowed by the font's license.
             case "linux":
             return "Ubuntu"
             default:
diff --git a/internal/frontend/bridge-gui/qml/Proton/Switch.qml b/internal/frontend/bridge-gui/qml/Proton/Switch.qml
index 9b85b768..5159c203 100644
--- a/internal/frontend/bridge-gui/qml/Proton/Switch.qml
+++ b/internal/frontend/bridge-gui/qml/Proton/Switch.qml
@@ -15,10 +15,10 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.12
-import QtQuick.Templates 2.12 as T
-import QtQuick.Controls 2.12
-import QtQuick.Controls.impl 2.12
+import QtQuick
+import QtQuick.Templates as T
+import QtQuick.Controls
+import QtQuick.Controls.impl
 
 T.Switch {
     property ColorScheme colorScheme
@@ -96,7 +96,7 @@ T.Switch {
                 sourceSize.width: 16
                 sourceSize.height: 16
                 color: "#FFFFFF"
-                source: "../icons/ic-check.svg"
+                source: "/qml/icons/ic-check.svg"
                 visible: control.checked
             }
 
@@ -116,7 +116,7 @@ T.Switch {
             sourceSize.width: 18
             sourceSize.height: 18
             color: control.colorScheme.interaction_norm_hover
-            source: "../icons/Loader_16.svg"
+            source: "/qml/icons/Loader_16.svg"
             visible: control.loading
 
             RotationAnimation {
@@ -140,11 +140,11 @@ T.Switch {
 
         color: control.enabled || control.loading ? control.colorScheme.text_norm : control.colorScheme.text_disabled
 
-        font.family: Style.font_family
-        font.weight: Style.fontWeight_400
-        font.pixelSize: Style.body_font_size
-        lineHeight: Style.body_line_height
+        font.family: ProtonStyle.font_family
+        font.weight: ProtonStyle.fontWeight_400
+        font.pixelSize: ProtonStyle.body_font_size
+        lineHeight: ProtonStyle.body_line_height
         lineHeightMode: Text.FixedHeight
-        font.letterSpacing: Style.body_letter_spacing
+        font.letterSpacing: ProtonStyle.body_letter_spacing
     }
 }
diff --git a/internal/frontend/bridge-gui/qml/Proton/TextArea.qml b/internal/frontend/bridge-gui/qml/Proton/TextArea.qml
index fad74f5f..91f367c8 100644
--- a/internal/frontend/bridge-gui/qml/Proton/TextArea.qml
+++ b/internal/frontend/bridge-gui/qml/Proton/TextArea.qml
@@ -15,12 +15,12 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQml 2.12
-import QtQuick 2.12
-import QtQuick.Controls 2.12
-import QtQuick.Controls.impl 2.12
-import QtQuick.Templates 2.12 as T
-import QtQuick.Layouts 1.12
+import QtQml
+import QtQuick
+import QtQuick.Controls
+import QtQuick.Controls.impl
+import QtQuick.Templates as T
+import QtQuick.Layouts
 
 import "." as Proton
 
@@ -198,10 +198,10 @@ FocusScope {
                 leftPadding: 12
                 rightPadding: 12
 
-                font.family: Style.font_family
-                font.weight: Style.fontWeight_400
-                font.pixelSize: Style.body_font_size
-                font.letterSpacing: Style.body_letter_spacing
+                font.family: ProtonStyle.font_family
+                font.weight: ProtonStyle.fontWeight_400
+                font.pixelSize: ProtonStyle.body_font_size
+                font.letterSpacing: ProtonStyle.body_letter_spacing
 
                 color: control.enabled ? root.colorScheme.text_norm : root.colorScheme.text_disabled
                 placeholderTextColor: control.enabled ? root.colorScheme.text_hint : root.colorScheme.text_disabled
@@ -233,7 +233,7 @@ FocusScope {
 
                     Connections {
                         target: control
-                        onCursorPositionChanged: {
+                        function onCursorPositionChanged() {
                             // keep a moving cursor visible
                             cursor.opacity = 1
                             timer.restart()
@@ -270,7 +270,7 @@ FocusScope {
                 background: Rectangle {
                     anchors.fill: parent
 
-                    radius: Style.input_radius
+                    radius: ProtonStyle.input_radius
                     visible: true
                     color: root.colorScheme.background_norm
                     border.color: {
@@ -308,7 +308,7 @@ FocusScope {
                 Layout.rightMargin: 4
 
                 visible: root.error && (assistiveText.text.length > 0)
-                source: "../icons/ic-exclamation-circle-filled.svg"
+                source: "/qml/icons/ic-exclamation-circle-filled.svg"
                 color: root.colorScheme.signal_danger
                 height: assistiveText.height
                 sourceSize.height: assistiveText.height
diff --git a/internal/frontend/bridge-gui/qml/Proton/TextField.qml b/internal/frontend/bridge-gui/qml/Proton/TextField.qml
index 621d7387..094e47d4 100644
--- a/internal/frontend/bridge-gui/qml/Proton/TextField.qml
+++ b/internal/frontend/bridge-gui/qml/Proton/TextField.qml
@@ -15,12 +15,12 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQml 2.12
-import QtQuick 2.12
-import QtQuick.Controls 2.12
-import QtQuick.Controls.impl 2.12
-import QtQuick.Templates 2.12 as T
-import QtQuick.Layouts 1.12
+import QtQml
+import QtQuick
+import QtQuick.Controls
+import QtQuick.Controls.impl
+import QtQuick.Templates as T
+import QtQuick.Layouts
 
 import "." as Proton
 
@@ -160,7 +160,7 @@ FocusScope {
             Layout.fillHeight: true
             Layout.fillWidth: true
 
-            radius: Style.input_radius
+            radius: ProtonStyle.input_radius
             visible: true
             color: root.colorScheme.background_norm
             border.color: {
@@ -208,10 +208,10 @@ FocusScope {
                     leftPadding: 12
                     rightPadding: 12
 
-                    font.family: Style.font_family
-                    font.weight: Style.fontWeight_400
-                    font.pixelSize: Style.body_font_size
-                    font.letterSpacing: Style.body_letter_spacing
+                    font.family: ProtonStyle.font_family
+                    font.weight: ProtonStyle.fontWeight_400
+                    font.pixelSize: ProtonStyle.body_font_size
+                    font.letterSpacing: ProtonStyle.body_letter_spacing
 
                     color: control.enabled ? root.colorScheme.text_norm : root.colorScheme.text_disabled
                     placeholderTextColor: control.enabled ? root.colorScheme.text_hint : root.colorScheme.text_disabled
@@ -243,7 +243,7 @@ FocusScope {
 
                         Connections {
                             target: control
-                            onCursorPositionChanged: {
+                            function onCursorPositionChanged() {
                                 // keep a moving cursor visible
                                 cursor.opacity = 1
                                 timer.restart()
diff --git a/internal/frontend/bridge-gui/qml/Proton/Toggle.qml b/internal/frontend/bridge-gui/qml/Proton/Toggle.qml
index 2236cc23..d6e32222 100644
--- a/internal/frontend/bridge-gui/qml/Proton/Toggle.qml
+++ b/internal/frontend/bridge-gui/qml/Proton/Toggle.qml
@@ -15,10 +15,10 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.13
-import QtQuick.Controls.impl 2.13
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
+import QtQuick.Controls.impl
 
 Item {
     id: root
@@ -72,7 +72,7 @@ Item {
 
             ColorImage {
                 anchors.centerIn: parent
-                source: "../icons/ic-check.svg"
+                source: "/qml/icons/ic-check.svg"
                 color: root.colorScheme.background_norm
                 height: root.colorScheme.body_font_size
                 sourceSize.height: root.colorScheme.body_font_size
@@ -83,7 +83,7 @@ Item {
         ColorImage {
             id: loader
             anchors.centerIn: parent
-            source: "../icons/Loader_16.svg"
+            source: "/qml/icons/Loader_16.svg"
             color: root.colorScheme.text_norm
             height: root.colorScheme.body_font_size
             sourceSize.height: root.colorScheme.body_font_size
diff --git a/internal/frontend/bridge-gui/qml/Proton/qmldir b/internal/frontend/bridge-gui/qml/Proton/qmldir
index c52bb8ef..b8750786 100644
--- a/internal/frontend/bridge-gui/qml/Proton/qmldir
+++ b/internal/frontend/bridge-gui/qml/Proton/qmldir
@@ -21,6 +21,7 @@ depends QtQuick.Controls 2.12
 singleton ProtonStyle 4.0 Style.qml
 ColorScheme 4.0 ColorScheme.qml
 
+Action 4.0 Action.qml
 ApplicationWindow 4.0 ApplicationWindow.qml
 Button 4.0 Button.qml
 CheckBox 4.0 CheckBox.qml
diff --git a/internal/frontend/bridge-gui/qml/SMTPSettings.qml b/internal/frontend/bridge-gui/qml/SMTPSettings.qml
index 7c713993..7a539129 100644
--- a/internal/frontend/bridge-gui/qml/SMTPSettings.qml
+++ b/internal/frontend/bridge-gui/qml/SMTPSettings.qml
@@ -15,12 +15,12 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.13
-import QtQuick.Controls.impl 2.13
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
+import QtQuick.Controls.impl
 
-import Proton 4.0
+import Proton
 
 SettingsView {
     id: root
@@ -87,7 +87,7 @@ SettingsView {
                 root.submit()
             }
 
-            enabled: sslButton.checked !== root.backend.useSSLforSMTP
+            enabled: sslButton.checked !== Backend.useSSLforSMTP
         }
 
         Button {
@@ -98,20 +98,22 @@ SettingsView {
         }
 
         Connections {
-            target: root.backend
+            target: Backend
 
-            onToggleUseSSLFinished: submitButton.loading = false
+            function onToggleUseSSLFinished() {
+                submitButton.loading = false
+            }
         }
     }
 
     function submit(){
         submitButton.loading = true
-        root.backend.toggleUseSSLforSMTP(sslButton.checked)
+        Backend.toggleUseSSLforSMTP(sslButton.checked)
     }
 
     function setDefaultValues(){
-        sslButton.checked = root.backend.useSSLforSMTP
-        starttlsButton.checked = !root.backend.useSSLforSMTP
+        sslButton.checked = Backend.useSSLforSMTP
+        starttlsButton.checked = !Backend.useSSLforSMTP
     }
 
     onVisibleChanged: {
diff --git a/internal/frontend/bridge-gui/qml/SettingsItem.qml b/internal/frontend/bridge-gui/qml/SettingsItem.qml
index 59dfd9d9..9085e1d3 100644
--- a/internal/frontend/bridge-gui/qml/SettingsItem.qml
+++ b/internal/frontend/bridge-gui/qml/SettingsItem.qml
@@ -15,11 +15,11 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
 
-import Proton 4.0
+import Proton
 
 Item {
     id: root
diff --git a/internal/frontend/bridge-gui/qml/SettingsView.qml b/internal/frontend/bridge-gui/qml/SettingsView.qml
index c436b953..75504b9c 100644
--- a/internal/frontend/bridge-gui/qml/SettingsView.qml
+++ b/internal/frontend/bridge-gui/qml/SettingsView.qml
@@ -15,18 +15,17 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.13
-import QtQuick.Controls.impl 2.13
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
+import QtQuick.Controls.impl
 
-import Proton 4.0
+import Proton
 
 Item {
     id: root
 
     property var colorScheme
-    property var backend
     default property alias items: content.children
 
     signal back()
@@ -92,7 +91,7 @@ Item {
         }
         colorScheme: root.colorScheme
         onClicked: root.back()
-        icon.source: "icons/ic-arrow-left.svg"
+        icon.source: "/qml/icons/ic-arrow-left.svg"
         secondary: true
         horizontalPadding: 8
     }
diff --git a/internal/frontend/bridge-gui/qml/SetupGuide.qml b/internal/frontend/bridge-gui/qml/SetupGuide.qml
index 3fb94efe..abed68eb 100644
--- a/internal/frontend/bridge-gui/qml/SetupGuide.qml
+++ b/internal/frontend/bridge-gui/qml/SetupGuide.qml
@@ -16,18 +16,17 @@
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
 
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
-import QtQuick.Controls.impl 2.12
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
+import QtQuick.Controls.impl
 
-import Proton 4.0
+import Proton
 
 Item {
     id:root
 
     property ColorScheme colorScheme
-    property var backend
     property var user
     property string address
 
@@ -41,29 +40,29 @@ Item {
     ListModel {
         id: clients
         property string name : "Apple Mail"
-        property string iconSource : "./icons/ic-apple-mail.svg"
+        property string iconSource : "/qml/icons/ic-apple-mail.svg"
         property bool haveAutoSetup: true
         property string link: "https://protonmail.com/bridge/applemail"
 
         Component.onCompleted : {
-            if (root.backend.goos == "darwin") {
+            if (Backend.goos == "darwin") {
                 append({
                     "name"          : "Apple Mail",
-                    "iconSource"    : "./icons/ic-apple-mail.svg",
+                    "iconSource"    : "/qml/icons/ic-apple-mail.svg",
                     "haveAutoSetup" : true,
                     "link"          : "https://protonmail.com/bridge/applemail"
                 })
                 append({
                     "name"          : "Microsoft Outlook",
-                    "iconSource"    : "./icons/ic-microsoft-outlook.svg",
+                    "iconSource"    : "/qml/icons/ic-microsoft-outlook.svg",
                     "haveAutoSetup" : false,
                     "link"          : "https://protonmail.com/bridge/outlook2019-mac"
                 })
             }
-            if (root.backend.goos == "windows") {
+            if (Backend.goos == "windows") {
                 append({
                     "name"          : "Microsoft Outlook",
-                    "iconSource"    : "./icons/ic-microsoft-outlook.svg",
+                    "iconSource"    : "/qml/icons/ic-microsoft-outlook.svg",
                     "haveAutoSetup" : false,
                     "link"          : "https://protonmail.com/bridge/outlook2019"
                 })
@@ -71,14 +70,14 @@ Item {
 
             append({
                 "name"          : "Mozilla Thunderbird",
-                "iconSource"    : "./icons/ic-mozilla-thunderbird.svg",
+                "iconSource"    : "/qml/icons/ic-mozilla-thunderbird.svg",
                 "haveAutoSetup" : false,
                 "link"          : "https://protonmail.com/bridge/thunderbird"
             })
 
             append({
                 "name"          : "Other",
-                "iconSource"    : "./icons/ic-other-mail-clients.svg",
+                "iconSource"    : "/qml/icons/ic-other-mail-clients.svg",
                 "haveAutoSetup" : false,
                 "link"          : "https://protonmail.com/bridge/clients"
             })
diff --git a/internal/frontend/bridge-gui/qml/SignIn.qml b/internal/frontend/bridge-gui/qml/SignIn.qml
index a39c00e0..72641743 100644
--- a/internal/frontend/bridge-gui/qml/SignIn.qml
+++ b/internal/frontend/bridge-gui/qml/SignIn.qml
@@ -15,13 +15,13 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQml 2.12
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
-import QtQuick.Controls.impl 2.12
+import QtQml
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
+import QtQuick.Controls.impl
 
-import Proton 4.0
+import Proton
 
 Item {
     id: root
@@ -37,14 +37,12 @@ Item {
 
     function abort() {
         root.reset()
-        root.backend.loginAbort(usernameTextField.text)
+        Backend.loginAbort(usernameTextField.text)
     }
 
     implicitHeight: children[0].implicitHeight
     implicitWidth: children[0].implicitWidth
 
-    property var backend
-
     property alias username: usernameTextField.text
     state: "Page 1"
 
@@ -65,9 +63,9 @@ Item {
         }
 
         Connections {
-            target: root.backend
+            target: Backend
 
-            onLoginUsernamePasswordError: {
+            function onLoginUsernamePasswordError(errorMsg) {
                 console.assert(stackLayout.currentIndex == 0, "Unexpected loginUsernamePasswordError")
                 console.assert(signInButton.loading == true, "Unexpected loginUsernamePasswordError")
 
@@ -76,23 +74,24 @@ Item {
                 else errorLabel.text = qsTr("Incorrect login credentials")
             }
 
-            onLoginFreeUserError: {
+            function onLoginFreeUserError() {
                 console.assert(stackLayout.currentIndex == 0, "Unexpected loginFreeUserError")
                 stackLayout.loginFailed()
             }
 
-            onLoginConnectionError: {
+            function onLoginConnectionError(errorMsg) {
                 if (stackLayout.currentIndex == 0 ) {
                     stackLayout.loginFailed()
                 }
             }
 
-            onLogin2FARequested: {
+            function onLogin2FARequested(username) {
                 console.assert(stackLayout.currentIndex == 0, "Unexpected login2FARequested")
                 twoFactorUsernameLabel.text = username
                 stackLayout.currentIndex = 1
             }
-            onLogin2FAError: {
+
+            function onLogin2FAError(errorMsg) {
                 console.assert(stackLayout.currentIndex == 1, "Unexpected login2FAError")
 
                 twoFAButton.loading = false
@@ -101,17 +100,18 @@ Item {
                 twoFactorPasswordTextField.error = true
                 twoFactorPasswordTextField.errorString = qsTr("Your code is incorrect")
             }
-            onLogin2FAErrorAbort: {
+
+            function onLogin2FAErrorAbort(errorMsg) {
                 console.assert(stackLayout.currentIndex == 1, "Unexpected login2FAErrorAbort")
                 root.reset()
                 errorLabel.text = qsTr("Incorrect login credentials. Please try again.")
             }
 
-            onLogin2PasswordRequested: {
+            function onLogin2PasswordRequested() {
                 console.assert(stackLayout.currentIndex == 0 || stackLayout.currentIndex == 1, "Unexpected login2PasswordRequested")
                 stackLayout.currentIndex = 2
             }
-            onLogin2PasswordError: {
+            function onLogin2PasswordError(errorMsg) {
                 console.assert(stackLayout.currentIndex == 2, "Unexpected login2PasswordError")
 
                 secondPasswordButton.loading = false
@@ -120,13 +120,13 @@ Item {
                 secondPasswordTextField.error = true
                 secondPasswordTextField.errorString = qsTr("Your mailbox password is incorrect")
             }
-            onLogin2PasswordErrorAbort: {
+            function onLogin2PasswordErrorAbort(errorMsg) {
                 console.assert(stackLayout.currentIndex == 2, "Unexpected login2PasswordErrorAbort")
                 root.reset()
                 errorLabel.text = qsTr("Incorrect login credentials. Please try again.")
             }
 
-            onLoginFinished: {
+            function onLoginFinished(index) {
                 stackLayout.currentIndex = 0
                 root.reset()
             }
@@ -179,7 +179,7 @@ Item {
 
                 ColorImage {
                     color: root.colorScheme.signal_danger
-                    source: "./icons/ic-exclamation-circle-filled.svg"
+                    source: "/qml/icons/ic-exclamation-circle-filled.svg"
                     height: errorLabel.height
                     sourceSize.height: errorLabel.height
                 }
@@ -274,7 +274,7 @@ Item {
                     enabled = false
                     loading = true
 
-                    root.backend.login(usernameTextField.text, Qt.btoa(passwordTextField.text))
+                    Backend.login(usernameTextField.text, Qt.btoa(passwordTextField.text))
                 }
             }
 
@@ -361,7 +361,7 @@ Item {
                     enabled = false
                     loading = true
 
-                    root.backend.login2FA(usernameTextField.text, Qt.btoa(twoFactorPasswordTextField.text))
+                    Backend.login2FA(usernameTextField.text, Qt.btoa(twoFactorPasswordTextField.text))
                 }
             }
         }
@@ -425,7 +425,7 @@ Item {
                     enabled = false
                     loading = true
 
-                    root.backend.login2Password(usernameTextField.text, Qt.btoa(secondPasswordTextField.text))
+                    Backend.login2Password(usernameTextField.text, Qt.btoa(secondPasswordTextField.text))
                 }
             }
         }
diff --git a/internal/frontend/bridge-gui/qml/SplashScreen.qml b/internal/frontend/bridge-gui/qml/SplashScreen.qml
index 22f93822..31e8d455 100644
--- a/internal/frontend/bridge-gui/qml/SplashScreen.qml
+++ b/internal/frontend/bridge-gui/qml/SplashScreen.qml
@@ -15,20 +15,18 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQml 2.12
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
-import QtQuick.Controls.impl 2.12
+import QtQml
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
+import QtQuick.Controls.impl
 
-import Proton 4.0
+import Proton
 
 Dialog {
     id: root
 
-    property var backend
-
-    shouldShow: root.backend.showSplashScreen
+    shouldShow: Backend.showSplashScreen
     modal: true
 
     topPadding   : 0
@@ -89,7 +87,7 @@ Dialog {
             Layout.rightMargin: 24
             colorScheme: root.colorScheme
             text: "Got it"
-            onClicked: root.backend.showSplashScreen = false
+            onClicked: Backend.showSplashScreen = false
         }
 
         Image {
@@ -101,7 +99,7 @@ Dialog {
             Layout.preferredWidth: 164
             Layout.preferredHeight: 32
 
-            source: "./icons/img-proton-logos.svg"
+            source: "/qml/icons/img-proton-logos.svg"
         }
     }
 }
diff --git a/internal/frontend/bridge-gui/qml/Status.qml b/internal/frontend/bridge-gui/qml/Status.qml
index addb7caf..8e86d541 100644
--- a/internal/frontend/bridge-gui/qml/Status.qml
+++ b/internal/frontend/bridge-gui/qml/Status.qml
@@ -16,18 +16,17 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
-import QtQuick.Controls.impl 2.12
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
+import QtQuick.Controls.impl
 
-import Proton 4.0
-import Notifications 1.0
+import Proton
+import Notifications
 
 Item {
     id: root
 
-    property var backend
     property var notifications
     property ColorScheme colorScheme
 
@@ -48,7 +47,7 @@ Item {
 
         onTopmostChanged: {
             if (!topmost) {
-                image.source = "./icons/ic-connected.svg"
+                image.source = "/qml/icons/ic-connected.svg"
                 image.color = root.colorScheme.signal_success
                 label.text = qsTr("Connected")
                 label.color = root.colorScheme.signal_success
@@ -89,7 +88,7 @@ Item {
             height: 16
             sourceSize.width: width
             sourceSize.height: height
-            source: "./icons/ic-connected.svg"
+            source: "/qml/icons/ic-connected.svg"
             color: root.colorScheme.signal_success
         }
 
diff --git a/internal/frontend/bridge-gui/qml/StatusWindow.qml b/internal/frontend/bridge-gui/qml/StatusWindow.qml
index d4dc1fa6..3fcfb0eb 100644
--- a/internal/frontend/bridge-gui/qml/StatusWindow.qml
+++ b/internal/frontend/bridge-gui/qml/StatusWindow.qml
@@ -15,14 +15,14 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQml 2.12
-import QtQuick 2.13
-import QtQuick.Window 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.13
+import QtQml
+import QtQuick
+import QtQuick.Window
+import QtQuick.Layouts
+import QtQuick.Controls
 
-import Proton 4.0
-import Notifications 1.0
+import Proton
+import Notifications
 
 Window {
     id: root
@@ -35,7 +35,6 @@ Window {
 
     property ColorScheme colorScheme: ProtonStyle.currentStyle
 
-    property var backend
     property var notifications
 
     signal showMainWindow()
@@ -114,7 +113,6 @@ Window {
                         Layout.bottomMargin: 12
 
                         colorScheme: root.colorScheme
-                        backend: root.backend
                         notifications: root.notifications
 
                         notificationWhitelist: Notifications.Group.Connection | Notifications.Group.Update | Notifications.Group.Configuration
@@ -164,7 +162,7 @@ Window {
             ListView {
                 id: accountListView
 
-                model: root.backend.users
+                model: Backend.users
                 anchors.fill: parent
 
                 anchors.topMargin: 8
@@ -185,7 +183,7 @@ Window {
                     implicitHeight: children[0].implicitHeight
                     implicitWidth: children[0].implicitWidth
 
-                    property var user: root.backend.users.get(index)
+                    property var user: Backend.users.get(index)
 
                     RowLayout {
                         spacing: 0
@@ -262,7 +260,7 @@ Window {
                 Button {
                     colorScheme: root.colorScheme
                     secondary: true
-                    icon.source: "./icons/ic-three-dots-vertical.svg"
+                    icon.source: "/qml/icons/ic-three-dots-vertical.svg"
                     borderless: true
                     checkable: true
 
diff --git a/internal/frontend/bridge-gui/qml/WelcomeGuide.qml b/internal/frontend/bridge-gui/qml/WelcomeGuide.qml
index d1efeb38..fa0bedea 100644
--- a/internal/frontend/bridge-gui/qml/WelcomeGuide.qml
+++ b/internal/frontend/bridge-gui/qml/WelcomeGuide.qml
@@ -15,20 +15,18 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQml 2.12
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
+import QtQml
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
 
-import Proton 4.0
+import Proton
 
 Item {
     id: root
 
     property ColorScheme colorScheme
 
-    property var backend
-
     implicitHeight: children[0].implicitHeight
     implicitWidth: children[0].implicitWidth
 
@@ -224,8 +222,7 @@ Item {
                         Layout.preferredWidth: 320
                         Layout.fillWidth: true
 
-                        username: root.backend.users.count === 1 && root.backend.users.get(0) && root.backend.users.get(0).loggedIn === false ? root.backend.users.get(0).username : ""
-                        backend: root.backend
+                        username: Backend.users.count === 1 && Backend.users.get(0) && Backend.users.get(0).loggedIn === false ? Backend.users.get(0).username : ""
                     }
 
                     // Right margin
diff --git a/internal/frontend/bridge-gui/qml/tests/Buttons.qml b/internal/frontend/bridge-gui/qml/tests/Buttons.qml
index c44feb4b..ed2c7a02 100644
--- a/internal/frontend/bridge-gui/qml/tests/Buttons.qml
+++ b/internal/frontend/bridge-gui/qml/tests/Buttons.qml
@@ -15,10 +15,10 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Window 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
+import QtQuick
+import QtQuick.Window
+import QtQuick.Layouts
+import QtQuick.Controls
 
 import "../Proton"
 
@@ -32,7 +32,7 @@ RowLayout {
         Layout.fillWidth: true
         Layout.fillHeight: true
 
-        iconLoading: "../icons/Loader_16.svg"
+        iconLoading: "/qml/icons/Loader_16.svg"
     }
 
     // Secondary buttons
@@ -42,7 +42,7 @@ RowLayout {
         Layout.fillHeight: true
 
         secondary: true
-        iconLoading: "../icons/Loader_16.svg"
+        iconLoading: "/qml/icons/Loader_16.svg"
     }
 
     // Secondary icons
@@ -53,11 +53,11 @@ RowLayout {
 
         secondary: true
         textNormal: ""
-        iconNormal: "../icons/ic-cross-close.svg"
+        iconNormal: "/qml/icons/ic-cross-close.svg"
         textDisabled: ""
-        iconDisabled: "../icons/ic-cross-close.svg"
+        iconDisabled: "/qml/icons/ic-cross-close.svg"
         textLoading: ""
-        iconLoading: "../icons/Loader_16.svg"
+        iconLoading: "/qml/icons/Loader_16.svg"
     }
 
     // Icons
@@ -67,10 +67,10 @@ RowLayout {
         Layout.fillHeight: true
 
         textNormal: ""
-        iconNormal: "../icons/ic-cross-close.svg"
+        iconNormal: "/qml/icons/ic-cross-close.svg"
         textDisabled: ""
-        iconDisabled: "../icons/ic-cross-close.svg"
+        iconDisabled: "/qml/icons/ic-cross-close.svg"
         textLoading: ""
-        iconLoading: "../icons/Loader_16.svg"
+        iconLoading: "/qml/icons/Loader_16.svg"
     }
 }
diff --git a/internal/frontend/bridge-gui/qml/tests/ButtonsColumn.qml b/internal/frontend/bridge-gui/qml/tests/ButtonsColumn.qml
index 988d5f89..55cc3ac0 100644
--- a/internal/frontend/bridge-gui/qml/tests/ButtonsColumn.qml
+++ b/internal/frontend/bridge-gui/qml/tests/ButtonsColumn.qml
@@ -15,9 +15,9 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick.Layouts 1.12
-import QtQuick 2.12
-import QtQuick.Controls 2.12
+import QtQuick.Layouts
+import QtQuick
+import QtQuick.Controls
 
 import "../Proton"
 
diff --git a/internal/frontend/bridge-gui/qml/tests/CheckBoxes.qml b/internal/frontend/bridge-gui/qml/tests/CheckBoxes.qml
index 18b86841..ca004740 100644
--- a/internal/frontend/bridge-gui/qml/tests/CheckBoxes.qml
+++ b/internal/frontend/bridge-gui/qml/tests/CheckBoxes.qml
@@ -15,10 +15,10 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Window 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
+import QtQuick
+import QtQuick.Window
+import QtQuick.Layouts
+import QtQuick.Controls
 
 import "../Proton"
 
diff --git a/internal/frontend/bridge-gui/qml/tests/ComboBoxes.qml b/internal/frontend/bridge-gui/qml/tests/ComboBoxes.qml
index c95e62ac..6bf9cefe 100644
--- a/internal/frontend/bridge-gui/qml/tests/ComboBoxes.qml
+++ b/internal/frontend/bridge-gui/qml/tests/ComboBoxes.qml
@@ -15,10 +15,10 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Window 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
+import QtQuick
+import QtQuick.Window
+import QtQuick.Layouts
+import QtQuick.Controls
 
 import "../Proton"
 
diff --git a/internal/frontend/bridge-gui/qml/tests/RadioButtons.qml b/internal/frontend/bridge-gui/qml/tests/RadioButtons.qml
index 2625f2c0..0ab51e95 100644
--- a/internal/frontend/bridge-gui/qml/tests/RadioButtons.qml
+++ b/internal/frontend/bridge-gui/qml/tests/RadioButtons.qml
@@ -15,10 +15,10 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Window 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
+import QtQuick
+import QtQuick.Window
+import QtQuick.Layouts
+import QtQuick.Controls
 
 import "../Proton"
 
diff --git a/internal/frontend/bridge-gui/qml/tests/Switches.qml b/internal/frontend/bridge-gui/qml/tests/Switches.qml
index eae07448..7d9b68af 100644
--- a/internal/frontend/bridge-gui/qml/tests/Switches.qml
+++ b/internal/frontend/bridge-gui/qml/tests/Switches.qml
@@ -15,10 +15,10 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Window 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
+import QtQuick
+import QtQuick.Window
+import QtQuick.Layouts
+import QtQuick.Controls
 
 import "../Proton"
 
diff --git a/internal/frontend/bridge-gui/qml/tests/Test.qml b/internal/frontend/bridge-gui/qml/tests/Test.qml
index 9093b33e..722d8465 100644
--- a/internal/frontend/bridge-gui/qml/tests/Test.qml
+++ b/internal/frontend/bridge-gui/qml/tests/Test.qml
@@ -15,7 +15,7 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick.Window 2.13
+import QtQuick.Window
 
 import "../Proton"
 
diff --git a/internal/frontend/bridge-gui/qml/tests/TestComponents.qml b/internal/frontend/bridge-gui/qml/tests/TestComponents.qml
index 61c12bdf..11f39ebd 100644
--- a/internal/frontend/bridge-gui/qml/tests/TestComponents.qml
+++ b/internal/frontend/bridge-gui/qml/tests/TestComponents.qml
@@ -15,9 +15,9 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
+import QtQuick
+import QtQuick.Layouts
+import QtQuick.Controls
 
 import "../Proton"
 
diff --git a/internal/frontend/bridge-gui/qml/tests/TextAreas.qml b/internal/frontend/bridge-gui/qml/tests/TextAreas.qml
index ba8632d9..c847e790 100644
--- a/internal/frontend/bridge-gui/qml/tests/TextAreas.qml
+++ b/internal/frontend/bridge-gui/qml/tests/TextAreas.qml
@@ -15,10 +15,10 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Window 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
+import QtQuick
+import QtQuick.Window
+import QtQuick.Layouts
+import QtQuick.Controls
 
 import "../Proton"
 
diff --git a/internal/frontend/bridge-gui/qml/tests/TextFields.qml b/internal/frontend/bridge-gui/qml/tests/TextFields.qml
index 6d83da5b..b687c7d0 100644
--- a/internal/frontend/bridge-gui/qml/tests/TextFields.qml
+++ b/internal/frontend/bridge-gui/qml/tests/TextFields.qml
@@ -15,10 +15,10 @@
 // You should have received a copy of the GNU General Public License
 // along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
 
-import QtQuick 2.13
-import QtQuick.Window 2.13
-import QtQuick.Layouts 1.12
-import QtQuick.Controls 2.12
+import QtQuick
+import QtQuick.Window
+import QtQuick.Layouts
+import QtQuick.Controls
 
 import "../Proton"