Change window close sequence to prompt user from Qml side

src/ui/MainWindow.cc

@@ -425,24 +425,20 @@ void MainWindow::showStatusBarCallback(bool checked)
     checked ? statusBar()->show() : statusBar()->hide();
 }
 
+void MainWindow::acceptWindowClose(void)
+{
+    qgcApp()->toolbox()->linkManager()->shutdown();
+    // The above shutdown causes a flurry of activity as the vehicle components are removed. This in turn
+    // causes the Windows Version of Qt to crash if you allow the close event to be accepted. In order to prevent
+    // the crash, we ignore the close event and setup a delayed timer to close the window after things settle down.
+    QTimer::singleShot(1500, this, &MainWindow::_closeWindow);
+}
+
 void MainWindow::closeEvent(QCloseEvent *event)
 {
     // Disallow window close if there are active connections
     if (qgcApp()->toolbox()->multiVehicleManager()->vehicles()->count()) {
-        QGCMessageBox::StandardButton button =
-            QGCMessageBox::warning(
-                tr("QGroundControl close"),
-                tr("There are still active connections to vehicles. Do you want to disconnect these before closing?"),
-                QMessageBox::Yes | QMessageBox::Cancel,
-                QMessageBox::Cancel);
-        if (button == QMessageBox::Yes) {
-            qgcApp()->toolbox()->linkManager()->shutdown();
-            // The above disconnect causes a flurry of activity as the vehicle components are removed. This in turn
-            // causes the Windows Version of Qt to crash if you allow the close event to be accepted. In order to prevent
-            // the crash, we ignore the close event and setup a delayed timer to close the window after things settle down.
-            QTimer::singleShot(1500, this, &MainWindow::_closeWindow);
-        }
-
+        emit showWindowCloseMessage();
         event->ignore();
         return;
     }

src/ui/MainWindow.h

@@ -91,6 +91,9 @@ public:
     /// @brief Saves the last used connection
     void saveLastUsedConnection(const QString connection);
 
+    // Called from MainWindow.qml when the user accepts the window close dialog
+    Q_INVOKABLE void acceptWindowClose(void);
+
 public slots:
     /** @brief Show the application settings */
     void showSettings();
@@ -132,6 +135,7 @@ protected slots:
      * this incoherent.
      */
     void handleActiveViewActionState(bool triggered);
+
 signals:
     // Signals the Qml to show the specified view
     void showFlyView(void);
@@ -139,6 +143,7 @@ signals:
     void showSetupView(void);
 
     void showToolbarMessage(const QString& message);
+    void showWindowCloseMessage(void);
 
     // These are used for unit testing
     void showSetupFirmware(void);

src/ui/MainWindow.qml

@@ -23,6 +23,7 @@ along with QGROUNDCONTROL. If not, see <http://www.gnu.org/licenses/>.
 
 import QtQuick          2.5
 import QtQuick.Controls 1.2
+import QtQuick.Dialogs  1.2
 import QtPositioning    5.2
 
 import QGroundControl                       1.0
@@ -95,6 +96,8 @@ Item {
 
         onShowToolbarMessage: toolBar.showToolbarMessage(message)
 
+        onShowWindowCloseMessage: windowCloseDialog.open()
+
         // The following are use for unit testing only
 
         onShowSetupFirmware:            setupViewLoader.item.showFirmwarePanel()
@@ -173,13 +176,24 @@ Item {
     function showPopUp(dropItem, centerX) {
         if(currentPopUp) {
             currentPopUp.close()
-        }
+          }
         indicatorDropdown.centerX = centerX
         indicatorDropdown.sourceComponent = dropItem
         indicatorDropdown.visible = true
         currentPopUp = indicatorDropdown
     }
 
+    MessageDialog {
+        id:                 windowCloseDialog
+        title:              "QGroundControl close"
+        text:               "There are still active connections to vehicles. Do you want to disconnect these before closing?"
+        standardButtons:    StandardButton.Yes | StandardButton.Cancel
+        modality:           Qt.ApplicationModal
+        visible:            false
+
+        onYes: controller.acceptWindowClose()
+    }
+
     //-- Left Settings Menu
     Loader {
         id:                 leftPanel