That it uses gtk theming from wine staging.

Feature Request

I confirm:

• that I haven't found another request for this feature.
• that I have checked whether there are updates for my system available that
  contain this feature already.

Description

That it uses the gtk theming option from wine staging,so that it looks like your gtk theme.

Justification [optional]

Cause steam uses Proton.

If that doesn't work that easily or causes problems,then it would be cool if proton would use this wine theme by default,cause it looks like windows 10.

Btw it would also be cool if you could set a custom msstyle to be used for every proton prefix.