Briefly;

First of all, I'm using motif style as the window style. It may be useful to say this before.

When I click the checkable property of a menu action, it puts an empty box near the action description and as you guess, when you select this action as the application is running, the box near the actions in filled or checked.

What I exactly want is to remove this box entirely and put my own icon whenever an action is selected from any menus stay at the menubar. But I couldn't do this yet.

By the way, I tried ::icon:checked{ image: url(foo.png)} but it didn't work.