Support for Rectmask2D?

[genaray]

Well its in the title... it works with standard masks but not with those.

I wonder if there's a way to combine them, like having a RoundedRectMask2D or something similar.

[Jepplen]

Support for RectMask2D was added in #35, are you on the latest commit?
If you mean to round the corners of a RectMask2D, I don't think that is the intended use, as then it sounds more like you want to use a normal Mask.
Looks like support was added for that in #39, a couple of weeks before you posted. :) Check the latest commit and see if that helps.