remove overlay of PortForward page because it will cause rebuilding when closing

msgbox
Signed-off-by: 21pages <pages21@163.com>

flutter/lib/desktop/pages/port_forward_page.dart

@@ -70,45 +70,38 @@ class _PortForwardPageState extends State<PortForwardPage>
   @override
   Widget build(BuildContext context) {
     super.build(context);
-    return Overlay(initialEntries: [
-      OverlayEntry(builder: (context) {
-        _ffi.dialogManager.setOverlayState(Overlay.of(context));
-        return Scaffold(
-          backgroundColor: MyTheme.color(context).grayBg,
-          body: FutureBuilder(future: () async {
-            if (!isRdp) {
-              refreshTunnelConfig();
-            }
-          }(), builder: (context, snapshot) {
-            if (snapshot.connectionState == ConnectionState.done) {
-              return Container(
-                decoration: BoxDecoration(
-                    border: Border.all(
-                        width: 20, color: MyTheme.color(context).grayBg!)),
-                child: Column(
-                  crossAxisAlignment: CrossAxisAlignment.stretch,
-                  children: [
-                    buildPrompt(context),
-                    Flexible(
-                      child: Container(
-                        decoration: BoxDecoration(
-                            color: MyTheme.color(context).bg,
-                            border:
-                                Border.all(width: 1, color: MyTheme.border)),
-                        child: widget.isRDP
-                            ? buildRdp(context)
-                            : buildTunnel(context),
-                      ),
-                    ),
-                  ],
+    return Scaffold(
+      backgroundColor: MyTheme.color(context).grayBg,
+      body: FutureBuilder(future: () async {
+        if (!isRdp) {
+          refreshTunnelConfig();
+        }
+      }(), builder: (context, snapshot) {
+        if (snapshot.connectionState == ConnectionState.done) {
+          return Container(
+            decoration: BoxDecoration(
+                border: Border.all(
+                    width: 20, color: MyTheme.color(context).grayBg!)),
+            child: Column(
+              crossAxisAlignment: CrossAxisAlignment.stretch,
+              children: [
+                buildPrompt(context),
+                Flexible(
+                  child: Container(
+                    decoration: BoxDecoration(
+                        color: MyTheme.color(context).bg,
+                        border: Border.all(width: 1, color: MyTheme.border)),
+                    child:
+                        widget.isRDP ? buildRdp(context) : buildTunnel(context),
+                  ),
                 ),
-              );
-            }
-            return const Offstage();
-          }),
-        );
-      })
-    ]);
+              ],
+            ),
+          );
+        }
+        return const Offstage();
+      }),
+    );
   }
 
   buildPrompt(BuildContext context) {