opt: windows and linux drag area

lib/app.dart

@@ -86,7 +86,8 @@ class MyApp extends StatelessWidget {
       themeMode: themeMode,
       theme: light.fixWindowsFont,
       darkTheme: (tMode < 3 ? dark : dark.toAmoled).fixWindowsFont,
-      home: Builder(
+      home: VirtualWindowFrame(
+        child: Builder(
           builder: (context) {
             context.setLibL10n();
             final appL10n = AppLocalizations.of(context);
@@ -100,6 +101,7 @@ class MyApp extends StatelessWidget {
             return const HomePage();
           },
         ),
+      ),
     );
   }
 }