Re: [PATCH v3 0/4] MR4888: wined3d: Avoid assuming the GL backend in (what can be) common code.

[Stefan Dösinger]

I just noticed this on wine-gitlab, and I am pretty sure the check was necessary at the time for the (IWineD3DTextureImpl *) stateblock->textures[0] cast.

Color keys have since been moved from surfaces to textures, and as Henri mentioned, textures unified. I don't know of a particular design reason why D3DRS_COLORKEYENABLE wouldn't work with cube textures. I don't know of any application that combines them though (the only ddraw thing I know that uses cube textures is a dx7 sdk sample), so I wouldn't be surprised if you hit driver bugs if you try.

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/4888#note_59255