support checking CheckMark::None

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

@@ -169,9 +169,6 @@ HRESULT AvnAppMenuItem::SetToggleType(AvnMenuItemToggleType toggleType)
         switch(toggleType)
         {
             case AvnMenuItemToggleType::None:
-                [_native setOnStateImage:nullptr];
-                break;
-                
             case AvnMenuItemToggleType::CheckMark:
                 [_native setOnStateImage: [NSImage imageNamed:@"NSMenuCheckmark"]];
                 break;

samples/ControlCatalog/MainWindow.xaml

@@ -39,6 +39,10 @@
       <NativeMenuItem Header="Options">
         <NativeMenuItem.Menu>
           <NativeMenu>
+           <NativeMenuItem Header="Check Me (None)" 
+                            Command="{Binding ToggleMenuItemCheckedCommand}"
+                            ToggleType="CheckBox"
+                            IsChecked="{Binding IsMenuItemChecked}"  />
             <NativeMenuItem Header="Check Me (CheckBox)" 
                             Command="{Binding ToggleMenuItemCheckedCommand}"
                             ToggleType="CheckBox"