Switch Theme to dark but partially invalid

I switch my theme to dark,but in design mode,my ui file still in light mode,this inharmony makes me uncomfortable.I found other people's Qt Creator has a dark theme with a dark ui,so I test Qt Creator of lower vesion,it turns out it surely a bug.

I've updated to 9.0.2,the latest version,it's still unresolved.

this is my bug pic:

this is normal pic: