I tried looking for any information regarding this, but surprisingly I couldn't find anything, despite this seeming like a pretty hard-to-miss issue. Krita seems to force the use of the 'Breeze' Qt style, even if I'm not using Breeze. The color scheme options built into Krita can be used to change the colors of course, but not the widget style. After looking into the 5.0 beta versions, it looks like you can select from a few different choices of widget styles now, (windows, fusion, etc) but no option to use the native Qt style. For my own case, I'm using a kvantum Qt theme with transparency effects, and nothing of this theme gets carried over to Krita. I don't really understand why this limitation is in place, or if it's done on purpose, but I just wanted some feedback on this since I couldn't find anything about it.