opt: move the resize area out of the flutter view

flutter/lib/desktop/pages/port_forward_tab_page.dart

@@ -109,11 +109,13 @@ class _PortForwardTabPageState extends State<PortForwardTabPage> {
     );
     return Platform.isMacOS
         ? tabWidget
-        : SubWindowDragToResizeArea(
-            child: tabWidget,
-            resizeEdgeSize: stateGlobal.resizeEdgeSize.value,
-            windowId: stateGlobal.windowId,
-          );
+        : Obx(
+          () => SubWindowDragToResizeArea(
+              child: tabWidget,
+              resizeEdgeSize: stateGlobal.resizeEdgeSize.value,
+              windowId: stateGlobal.windowId,
+            ),
+        );
   }
 
   void onRemoveId(String id) {

flutter/lib/desktop/pages/remote_tab_page.dart

@@ -210,6 +210,8 @@ class _ConnectionTabPageState extends State<ConnectionTabPage> {
         : Obx(() => SubWindowDragToResizeArea(
               key: contentKey,
               child: tabWidget,
+              // Specially configured for a better resize area and remote control.
+              childPadding: kDragToResizeAreaPadding,
               resizeEdgeSize: stateGlobal.resizeEdgeSize.value,
               windowId: stateGlobal.windowId,
             ));

flutter/lib/desktop/screen/desktop_remote_screen.dart

@@ -1,3 +1,5 @@
+import 'dart:io';
+
 import 'package:flutter/material.dart';
 import 'package:flutter_hbb/common.dart';
 import 'package:flutter_hbb/desktop/pages/remote_tab_page.dart';
@@ -26,6 +28,9 @@ class DesktopRemoteScreen extends StatelessWidget {
           ChangeNotifierProvider.value(value: gFFI.canvasModel),
         ],
         child: Scaffold(
+          // Set transparent background for padding the resize area out of the flutter view.
+          // This allows the wallpaper goes through our resize area. (Linux only now).
+          backgroundColor: Platform.isLinux ? Colors.transparent : null,
           body: ConnectionTabPage(
             params: params,
           ),

flutter/lib/desktop/widgets/tabbar_widget.dart

@@ -523,12 +523,18 @@ class WindowActionPanelState extends State<WindowActionPanel>
     super.dispose();
   }
 
+  void _setMaximize(bool maximize) {
+     stateGlobal.setMaximize(maximize);
+     setState(() {});
+  }
+
   @override
   void onWindowMaximize() {
     // catch maximize from system
     if (!widget.isMaximized.value) {
       widget.isMaximized.value = true;
     }
+    _setMaximize(true);
     super.onWindowMaximize();
   }
 
@@ -538,6 +544,7 @@ class WindowActionPanelState extends State<WindowActionPanel>
     if (widget.isMaximized.value) {
       widget.isMaximized.value = false;
     }
+    _setMaximize(false);
     super.onWindowUnmaximize();
   }