Merge pull request #3338 from Kingtous/master

opt: lack of frame border in remote page

flutter/lib/desktop/pages/file_manager_tab_page.dart

@@ -86,14 +86,18 @@ class _FileManagerTabPageState extends State<FileManagerTabPage> {
 
   @override
   Widget build(BuildContext context) {
-    final tabWidget = Scaffold(
-        backgroundColor: Theme.of(context).cardColor,
-        body: DesktopTab(
-          controller: tabController,
-          onWindowCloseButton: handleWindowCloseButton,
-          tail: const AddButton().paddingOnly(left: 10),
-          labelGetter: DesktopTab.labelGetterAlias,
-        ));
+    final tabWidget = Container(
+      decoration: BoxDecoration(
+          border: Border.all(color: MyTheme.color(context).border!)),
+      child: Scaffold(
+          backgroundColor: Theme.of(context).cardColor,
+          body: DesktopTab(
+            controller: tabController,
+            onWindowCloseButton: handleWindowCloseButton,
+            tail: const AddButton().paddingOnly(left: 10),
+            labelGetter: DesktopTab.labelGetterAlias,
+          )),
+    );
     return Platform.isMacOS
         ? tabWidget
         : SubWindowDragToResizeArea(