Can toggle fullscreen on calls

lib/ui/widgets/tablet_mode/calls/call_window_widget.dart

@@ -29,6 +29,10 @@ class CallWindowWidget extends StatefulWidget {
 class _CallWindowWidgetState extends State<CallWindowWidget> {
   double _left, _top;
 
+  var _fullScreen = false;
+
+  final _callScreenKey = GlobalKey();
+
   @override
   void didChangeDependencies() {
     super.didChangeDependencies();
@@ -40,6 +44,8 @@ class _CallWindowWidgetState extends State<CallWindowWidget> {
 
   @override
   Widget build(BuildContext context) {
+    if (_fullScreen) return _buildScreen();
+
     return Positioned(
       width: _WindowSize.width,
       height: _WindowSize.height,
@@ -47,24 +53,7 @@ class _CallWindowWidgetState extends State<CallWindowWidget> {
       top: _top,
       child: Draggable(
         child: Card(
-          child: CallScreen(
+          child: _buildScreen(),
-            buildCustomAppBar: (convName) => AppBarWrapper(
-                height: 30,
-                appBar: AppBar(
-                  backgroundColor: Colors.black,
-                  title: Text(convName == null ? tr("Loading...") : convName),
-                  actions: <Widget>[
-                    IconButton(
-                      iconSize: 16,
-                      icon: Icon(Icons.close),
-                      onPressed: widget.onClose,
-                    )
-                  ],
-                )),
-            convID: widget.convID,
-            floatingButtons: false,
-            onClose: widget.onClose,
-          ),
         ),
         feedback: Container(
           width: _WindowSize.width,
@@ -76,6 +65,35 @@ class _CallWindowWidgetState extends State<CallWindowWidget> {
     );
   }
 
+  Widget _buildScreen() => CallScreen(
+        key: _callScreenKey,
+        buildCustomAppBar: (convName) => AppBarWrapper(
+            height: 30,
+            appBar: AppBar(
+              backgroundColor: Colors.black,
+              title: Text(convName == null ? tr("Loading...") : convName),
+              actions: <Widget>[
+                // Go full screen
+                IconButton(
+                  iconSize: 16,
+                  icon: Icon(
+                      _fullScreen ? Icons.fullscreen_exit : Icons.fullscreen),
+                  onPressed: _toggleFullScreen,
+                ),
+
+                // Close call
+                IconButton(
+                  iconSize: 16,
+                  icon: Icon(Icons.close),
+                  onPressed: widget.onClose,
+                )
+              ],
+            )),
+        convID: widget.convID,
+        floatingButtons: _fullScreen,
+        onClose: widget.onClose,
+      );
+
   /// Compute new window position
   void _moveEnd(DraggableDetails details) {
     // Determine the limits of containing stack
@@ -101,4 +119,6 @@ class _CallWindowWidgetState extends State<CallWindowWidget> {
 
     setState(() {});
   }
+
+  void _toggleFullScreen() => setState(() => _fullScreen = !_fullScreen);
 }