Allow custom plugins to define the use of mobile file dialog regardless of the actual platform.

src/QmlControls/QGCFileDialog.qml

@@ -25,7 +25,7 @@ Item {
 
     property bool   _openForLoad:   true
     property real   _margins:       ScreenTools.defaultFontPixelHeight / 2
-    property bool   _mobile:        ScreenTools.isMobile
+    property bool   _mobileDlg:     QGroundControl.corePlugin.options.useMobileFileDialog
     property var    _rgExtensions
 
     Component.onCompleted: {
@@ -39,7 +39,7 @@ Item {
 
     function openForLoad() {
         _openForLoad = true
-        if (_mobile && folder.length !== 0) {
+        if (_mobileDlg && folder.length !== 0) {
             qgcView.showDialog(mobileFileOpenDialog, title, qgcView.showDialogDefaultWidth, StandardButton.Cancel)
         } else {
             fullFileDialog.open()
@@ -48,7 +48,7 @@ Item {
 
     function openForSave() {
         _openForLoad = false
-        if (_mobile && folder.length !== 0) {
+        if (_mobileDlg && folder.length !== 0) {
             qgcView.showDialog(mobileFileSaveDialog, title, qgcView.showDialogDefaultWidth, StandardButton.Cancel | StandardButton.Ok)
         } else {
             fullFileDialog.open()

src/api/QGCOptions.h

@@ -44,6 +44,7 @@ public:
     Q_PROPERTY(bool                     multiVehicleEnabled             READ multiVehicleEnabled            NOTIFY multiVehicleEnabledChanged)
     Q_PROPERTY(bool                     showOfflineMapExport            READ showOfflineMapExport           NOTIFY showOfflineMapExportChanged)
     Q_PROPERTY(bool                     showOfflineMapImport            READ showOfflineMapImport           NOTIFY showOfflineMapImportChanged)
+    Q_PROPERTY(bool                     useMobileFileDialog             READ useMobileFileDialog            CONSTANT)
 
     /// Should QGC hide its settings menu and colapse it into one single menu (Settings and Vehicle Setup)?
     /// @return true if QGC should consolidate both menus into one.
@@ -80,9 +81,11 @@ public:
 #if defined(__mobile__)
     virtual bool    showOfflineMapExport            () const { return false; }
     virtual bool    showOfflineMapImport            () const { return false; }
+    virtual bool    useMobileFileDialog             () const { return true;}
 #else
     virtual bool    showOfflineMapExport            () const { return true; }
     virtual bool    showOfflineMapImport            () const { return true; }
+    virtual bool    useMobileFileDialog             () const { return false;}
 #endif
 
     /// If returned QString in non-empty it means that firmware upgrade will run in a mode which only