Thanks. This was an Objo Studio bug.
The main Add menu and the Solution Navigator context menus were maintained separately. The Navigator menu was missing Window, Menu Bar, and Toolbar, even though all three can validly be added to a project or source folder.
I’ve fixed the context menus so application projects and folders now offer those visual source items alongside the existing choices. Test folders remain restricted to test-compatible items.
This fix will be in the next release: https://feedback.objo.dev/bug/1239