[Kst] Changes to look of dialogue boxes

[Nicolas Brisset]

Hi Peter,

> Here the diff betweenn 2.0.4 and 2.0.5:
> 
> https://github.com/syntheticpp/kst/compare/2.0.4...2.0.5#files_bucket
> 
> But I couldn't find a style specific change.
> Maybe a new CMake version?
Could it be that you changed something ou your machine, where you build the Windows binaries? I seem to have the same effect on my Windows machine...

Nicolas