correctly handle changes on app menu

native/Avalonia.Native/src/OSX/menu.mm

@@ -217,8 +217,18 @@ extern void SetAppMenu (NSString* appName, IAvnAppMenu* menu)
     {
         auto nativeMenu = dynamic_cast<AvnAppMenu*>(s_appMenu);
         
+        auto currentMenu = [s_appMenuItem menu];
+        
+        [currentMenu removeItem:s_appMenuItem];
+        
         s_appMenuItem = [nativeMenu->GetNative() itemAtIndex:0];
         
+        [[s_appMenuItem menu] removeItem:s_appMenuItem];
+        
+        [currentMenu insertItem:s_appMenuItem atIndex:0];
+        
+        //[NSApp setMenu:nativeMenu->GetNative()];
+        
         auto appMenu  = [s_appMenuItem submenu];
         [appMenu addItem:[NSMenuItem separatorItem]];
         

samples/ControlCatalog/App.xaml

@@ -20,13 +20,19 @@
 
   <NativeMenu.Menu>
     <NativeMenu>
-      <NativeMenuItem Header="Open" Clicked="OnOpenClicked"/>
-      <NativeMenuItem Header="Recent">
+      <NativeMenuItem>
         <NativeMenuItem.Menu>
-          <NativeMenu/>
+          <NativeMenu>
+            <NativeMenuItem Header="Open" Clicked="OnOpenClicked"/>
+            <NativeMenuItem Header="Recent">
+              <NativeMenuItem.Menu>
+                <NativeMenu/>
+              </NativeMenuItem.Menu>
+            </NativeMenuItem>
+            <NativeMenuItem Header="Quit Avalonia" Gesture="CMD+Q"/>
+          </NativeMenu>
         </NativeMenuItem.Menu>
       </NativeMenuItem>
-      <NativeMenuItem Header="Quit Avalonia" Gesture="CMD+Q"/>
     </NativeMenu>
   </NativeMenu.Menu>
 </Application>

samples/ControlCatalog/App.xaml.cs

@@ -16,7 +16,7 @@ namespace ControlCatalog
 
             Name = "Avalonia";
 
-            _recentMenu = (NativeMenu.GetMenu(this).Items[1] as NativeMenuItem).Menu;
+            _recentMenu = ((NativeMenu.GetMenu(this).Items[0] as NativeMenuItem).Menu.Items[1] as NativeMenuItem).Menu;
         }
 
         public void OnOpenClicked(object sender, EventArgs args)