When I set custom shortcuts that make use of the Hyper modifier and press Save, I am unable to trigger the actions that I've defined Hyper key modifier shortcuts for. Navigating back to my custom shortcuts, I see that the settings didn't actually save as expected: Krita appears to have garbled or threw away the "modifier" part of the shortcut.

(Also, the way the Hyper shortcut is displayed is very strange, but that is a different bug. I believe it is beyond the scope of Krita as some other KDE software also display Hyper key shortcuts the same way, see Additional Information)

Reproducible: Always

Steps to Reproduce:
1. Use xmodmap to bind a keycode (eg the keycode for Caps Lock) to a Hyper keysym (either Hyper_L or Hyper_R), then bind the keysym to an empty modifier (mod3 is often empty). Confirm the keycode actually sends the Hyper keysym using a tool like xev.
2. In Krita, define a keyboard shortcut for About Krita that uses the Hyper modifier (like Hyper + a)
3. Save the new settings
4. Press the new keyboard shortcut for About Krita (whatever it is)

Actual Results:  
Nothing, the About Krita window does not appear.

Expected Results:  
The About Krita window pops up.

My copy of the Krita 3.0 binary is self compiled from the git repo.

I used xmodmap to make my Caps Lock key behave as a "Hyper" modifier key, the Hyper key is essentially just another modifier, exactly like Ctrl and Alt: In X, the following modifier keysyms are recognized: Shift, Ctrl, Alt, Meta, Super, Hyper, and Mode Switch. These keysyms can be bound in many ways to the following "modifiers": shift, lock, control, mod1, mod2, mod3, mod4, and mod5. Generally the Alt and Meta keysyms are not distinguished and may even be bound to the same modifier. Super is usually on it's own modifier, and oftentimes it is the keysym that is sent by the Windows key. Hyper is almost always unbound to any keycode, or at least not a keycode that can be sent by an everyday keyboard, that same can be said for Mode Switch. Additional information on xmodmap: https://wiki.archlinux.org/index.php/xmodmap

Below is my configuration. Hyper is on it's own modifer, and is bound to the keycode for Caps Lock. Frankly I don't understand X enough to know why keysyms like Alt and Hyper are not the "same thing" as modifiers like shift, lock, mod1, mod2, etc. I'm not sure what those "modifiers" even are.

I've configured my keysyms and keycodes like so:
$ xmodmap
xmodmap:  up to 2 keys per modifier, (keycodes in parentheses):

shift       Shift_L (0x32),  Mode_switch (0x3e)
lock      
control     Control_L (0x25)
mod1        Meta_L (0x40),  Meta_L (0xcd)
mod2        Alt_L (0x6c),  Alt_L (0xcc)
mod3        Hyper_L (0x42),  Hyper_L (0xcf)
mod4        Super_L (0x85),  Super_L (0xce)
mod5      

https://doc.qt.io/qt-5/qkeyevent.html
Qt docs suggest that the Hyper modifier event isn't actually supported (no mention of Hyper)

https://imgur.com/a/LFstj
The way Hyper is displayed in various KDE software is very strange, but unlike Krita the Hyper shortcuts do actually work.  I have never seen the symbol before and have no clue what it is, and it seems to suggest that Qt indeed doesn't actually know how to handle Hyper key events.

https://i.imgur.com/DLFoE8v.png
GIMP handles the Hyper key as expected. Even though it makes use of a different GUI toolkit, I think it is also a good example for how Krita could better handle the Hyper key.