Wine + 3.3.5 client does not receive specific keyboard inputs

Hello,

I recently changed my OS from Windows to Kubuntu and was trying out if I can do everything I did before. During the first RDF I already realized that WoW is misbehaving, some actions which I requested never actually fired. The issue is it seems something is binding some special key combinations and therefore the client never actually receives it. Shift + Right mouse button + 3, Shift + 4, Shift + 5 just to name a few.
I also realized that there is a small icon on the top-left corner when the combination is swallowed, see in screenshot... like if you start to type somewhere.
https://www.aecentral.org/WoW_Wine.png

I looked up some guides and tried:
- RawMouseMode
- OffscreenRenderingMode, MouseWarpOverride
- Swapping to Win 7 in Wine
- Playing around with the options in winecfg

My guess is whatever it is it will be a feature of Wine as this does not happen with native applications. However as I have little to no experience with Linux and WoW in general, any help would be greatly appreciated :)

That looks like an IME to me such as ibus or fcitx.

Spot on :)

The strange icon in the top-left disappeared when in regional settings I turned off some new input method under the keyboard, but the keypress was still swallowed. Then I went on and removed fcitx from the system, without success. Lastly, as im-config still reported chinese and english layouts (which I'm not using, have no idea where those came from) I went on and cleared all values from /etc/default/im-config. Settings are there, but all values are empty.

Now, I don't know which of the above actually solved the problem (as I only rebooted after all was doen) but at the moment no more icon in top left, key presses seem to be sent to the WoW client :)

Thank you for the assistance!