Created attachment 123315 [details]
Screenshot of Krita without menu

SUMMARY
When fcitx (East-Asian / CJK input method) is used as the Qt IM module, and the Plasma global menu is active, Krita's global does not appear. Because the menu does not appear in the Krita window itself either, this makes Krita unusable for fcitx users, because menu commands are completely inaccessible.

This was reported before by Vladimir Yerilov in an unrelated closed bug (https://bugs.kde.org/show_bug.cgi?id=408015#c34).

STEPS TO REPRODUCE
(Tested on a freshly installed Kubuntu 19.10 VM.)
1. Right-click on the desktop, and do `Add Panel > Application Menu Bar`.
2. Open Konsole and verify the global menu bar works.
3. Install fcitx: `sudo apt install fcitx-bin`.
4. Install Krita: `sudo apt install krita`.
5. Run `QT_IM_MODULE=fcitx krita`.

OBSERVED RESULT
No menu is present in the global menu, and the menu is not present in the Krita window either (see attached screenshot). Hence, the menu cannot be accessed.
In any other KDE/Qt applications (e.g. Konsole, Dolphin, Kate, Gwenview, ...) the global menu works correctly.

EXPECTED RESULT
The global menu is present, or alternatively the menu is at least present in the Krita window itself.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Kubuntu 19.10 (Eoan)
KDE Plasma Version: 5.16.5
KDE Frameworks Version: 5.62.0
Qt Version: 5.12.4
Krita Version: 4.2.7.1

ADDITIONAL INFORMATION
It looks like fcitx does not actually need to be running to trigger the bug. It being installed (and QT_IM_MODULE being set to `fcitx`) is enough to trigger the bug.

I do not know if this is a bug in the QPA, fcitx, or Krita, but I reported it in Krita due to the fact that it occurs only in Krita (and not in other applications).