fix: distinguish request approval submenus on mobile

flutter/lib/common/widgets/request_approval_menu.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 
+import '../../common.dart';
 import '../../desktop/widgets/material_mod_popup_menu.dart' as mod_menu;
 import '../../desktop/widgets/popup_menu.dart';
 
@@ -33,10 +34,13 @@ class RequestApprovalMenu extends MenuEntryBase<String> {
       text: title,
       dismissParentOnCanceled: true,
       arrowScale: arrowScale,
+      barrierColor: isMobile ? Colors.black26 : null,
       padding: (padding ?? EdgeInsets.zero)
           .copyWith(right: (padding?.right ?? 0) + arrowInset),
-      entries: entries
-          .map((entry) => MenuEntryButton<String>(
+      entries: [
+        if (isMobile)
+          _RequestApprovalMenuTitle(title, padding),
+        ...entries.map((entry) => MenuEntryButton<String>(
                 childBuilder: entry.childBuilder,
                 proc: entry.proc,
                 padding: entry.padding,
@@ -45,8 +49,39 @@ class RequestApprovalMenu extends MenuEntryBase<String> {
                 dismissCallback: () {
                   if (Navigator.canPop(context)) Navigator.pop(context);
                 },
-              ))
-          .toList(),
+              )),
+      ],
     ).build(context, conf);
   }
 }
+
+class _RequestApprovalMenuTitle extends MenuEntryBase<String> {
+  final String title;
+  final EdgeInsets? padding;
+
+  _RequestApprovalMenuTitle(this.title, this.padding);
+
+  @override
+  List<mod_menu.PopupMenuEntry<String>> build(
+      BuildContext context, MenuConfig conf) => [
+        mod_menu.PopupMenuItem<String>(
+          enabled: false,
+          height: conf.height,
+          padding: EdgeInsets.zero,
+          child: TextButton(
+            onPressed: null,
+            child: Container(
+              alignment: AlignmentDirectional.centerStart,
+              height: conf.height,
+              padding: padding,
+              child: Semantics(
+                header: true,
+                child: Text(title,
+                    style: enabledStyle(context)
+                        .copyWith(fontWeight: FontWeight.w600)),
+              ),
+            ),
+          ),
+        ),
+      ];
+}