Improve linux window.

lib/components/window_frame.dart

@@ -147,7 +147,8 @@ class _WindowFrameState extends State<WindowFrame> {
                             onPressed: debug,
                             child: Text('Debug'),
                           ),
-                        if (!App.isMacOS) _WindowButtons(
+                        if (!App.isMacOS)
+                          _WindowButtons(
                             onClose: _onClose,
                           )
                       ],
@@ -559,22 +560,19 @@ class _VirtualWindowFrameState extends State<VirtualWindowFrame>
   }
 
   Widget _buildVirtualWindowFrame(BuildContext context) {
-    return DecoratedBox(
+    return Container(
         decoration: BoxDecoration(
+          borderRadius: BorderRadius.circular(_isMaximized ? 0 : 8),
           color: Colors.transparent,
-        border: Border.all(
-          color: Theme.of(context).dividerColor,
-          width: (_isMaximized || _isFullScreen) ? 0 : 1,
-        ),
           boxShadow: <BoxShadow>[
-          if (!_isMaximized && !_isFullScreen)
             BoxShadow(
-              color: Colors.black.toOpacity(0.1),
+                color: Colors.black.toOpacity(_isFocused ? 0.4 : 0.2),
-              offset: Offset(0.0, _isFocused ? 4 : 2),
+                offset: Offset(0.0, 2),
-              blurRadius: 6,
+                blurRadius: 4,
               )
           ],
         ),
+        clipBehavior: Clip.antiAlias,
         child: widget.child,
       );
   }
@@ -583,7 +581,10 @@ class _VirtualWindowFrameState extends State<VirtualWindowFrame>
   Widget build(BuildContext context) {
     return DragToResizeArea(
       enableResizeEdges: (_isMaximized || _isFullScreen) ? [] : null,
+      child: Padding(
+        padding: EdgeInsets.all(_isMaximized ? 0 : 4),
         child: _buildVirtualWindowFrame(context),
+      ),
     );
   }
 

lib/main.dart

@@ -34,13 +34,10 @@ void main(List<String> args) {
             await windowManager.setBackgroundColor(Colors.transparent);
           }
           await windowManager.setMinimumSize(const Size(500, 600));
-          if (!App.isLinux) {
-            // https://github.com/leanflutter/window_manager/issues/460
           var placement = await WindowPlacement.loadFromFile();
           await placement.applyToWindow();
           await windowManager.show();
           WindowPlacement.loop();
-          }
         });
       }
     }, (error, stack) {
@@ -201,6 +198,7 @@ class _MyAppState extends State<MyApp> with WidgetsBindingObserver {
           'dark' => ThemeMode.dark,
           _ => ThemeMode.system
         },
+        color: Colors.transparent,
         localizationsDelegates: [
           GlobalMaterialLocalizations.delegate,
           GlobalCupertinoLocalizations.delegate,
@@ -248,6 +246,7 @@ class _MyAppState extends State<MyApp> with WidgetsBindingObserver {
               );
             }
             return _SystemUiProvider(Material(
+              color: App.isLinux ? Colors.transparent : null,
               child: widget,
             ));
           }

linux/my_application.cc

@@ -48,6 +48,12 @@ static void my_application_activate(GApplication* application) {
   }
 
   gtk_window_set_default_size(window, 1280, 720);
+  GdkVisual* visual;
+  gtk_widget_set_app_paintable(GTK_WIDGET(window), TRUE);
+  visual = gdk_screen_get_rgba_visual(screen);
+  if (visual != NULL && gdk_screen_is_composited(screen)) {
+    gtk_widget_set_visual(GTK_WIDGET(window), visual);
+  }
   gtk_widget_show(GTK_WIDGET(window));
 
   g_autoptr(FlDartProject) project = fl_dart_project_new();
@@ -58,6 +64,7 @@ static void my_application_activate(GApplication* application) {
   gtk_container_add(GTK_CONTAINER(window), GTK_WIDGET(view));
 
   fl_register_plugins(FL_PLUGIN_REGISTRY(view));
+  gtk_widget_hide(GTK_WIDGET(window));
 
   gtk_widget_grab_focus(GTK_WIDGET(view));
 }