With i3(gaps) running on top of Manjaro KDE Edition, it seems I am not able to change my menu bar (File, Edit, View, etc). The original Issue was that it is displayed in Atom, where I neither need nor want it. Trying the different settings in system setting -> Application Style -> Widget Style and Behaviour -> Fine Tuning -> Menubar Style and restarting Atom, the menu bar would not change at all. Meanwhile Dolphin had no menu bar displayed, which stays unaffected by settings as well. Furthermore Ctrl+M and Ctrl+Shift+M had no effect.
So my question is, how can I enable/disable the menu bar? (especially for Atom, but for other apps would be interesting as well)