refact: window frame border (#7946)

Signed-off-by: fufesou <shuanglongchen@yeah.net>

flutter/lib/desktop/widgets/tabbar_widget.dart

@@ -548,6 +548,16 @@ class WindowActionPanelState extends State<WindowActionPanel>
     setState(() {});
   }
 
+  @override
+  void onWindowFocus() {
+    stateGlobal.isFocused.value = true;
+  }
+
+  @override
+  void onWindowBlur() {
+    stateGlobal.isFocused.value = false;
+  }
+
   @override
   void onWindowMinimize() {
     stateGlobal.setMinimized(true);