I'm using KWin 18.104.22.168 from Kubuntu Focal. This is the first time I'm getting exposed to the integration of the App Menu into the decoration since I'm upgrading directly from Bionic. I have not installed any global menu widget.
I find that the keyboard navigation for the app menu is seriously faulty. I give examples using the simple basic app Kate.
1) If I open the App Menu by clicking on the decoration button using the mouse, I am able to use Up/Down to navigate among File, Edit etc. I am also able to use Right to enter a submenu.
2) If I once enter one of these submenus from the above step, or if I directly do Alt+F etc to go to these submenus, I can similarly navigate Up/Down or enter further submenus. For instance, in File, I can go under Open Recent.
3) However I cannot go back to a parent menu/submenu at any stage by using Left.
a) If I try to do that from a sub-sub-menu like Open Recent, the whole menu is exited and the focus goes back to the application wherever it was.
b) If I try to do that from within a top-level sub-menu like File, I am brought back to the top-level menu but unable to use Up/Down to navigate between File, Edit etc as before. Even Esc doesn't enable one to exit the menu. It is effectively frozen for normal navigation.
c) Surprisingly, pressing Alt+Tab or Alt+BackTab at this point enables one to navigate instead. If once we press either of these two then normal navigation of Up/Down or Esc is restored.
At all points of time, mouse navigation of the menu/submenus works fine AFAICS, but this doesn't help people like me who are devoted to the keyboard.
For now I'm switching off the in-decoration app menu due this serious usability problem. Doing so also doesn't seem to awaken all apps immediately to restore their regular menu bars, but that's a separate problem.
I hope this can be fixed.
Linux/KDE Plasma: Kubuntu Focal
(available in About System)
KDE Plasma Version: 22.214.171.124
KDE Frameworks Version: 5.68.0
Qt Version: 5.12.8
A possibly relevant merge request was started @ https://invent.kde.org/plasma/plasma-workspace/-/merge_requests/839
Git commit f8dcf69718f0d1e85632b4500994b4812621a88b by David Redondo.
Committed on 12/05/2021 at 10:19.
Pushed by davidre into branch 'master'.
Drop input grabbing hack
Apparently this was introduced to prevent the window losing focus if
https://bugs.kde.org/show_bug.cgi?id=310476 is to be believed. However
on X the window does not lose focus without it.
Furthermore it actually improves keyboard navigation on X, which after a
child menu was closed stopped working.
On Wayland this prevents things working at all.
M +0 -37 appmenu/verticalmenu.cpp
M +0 -7 appmenu/verticalmenu.h