Ah, I read that three times on the site but it didn't sink in until I saw your comment. I guess with a title like "GUI toolkit" my expectations were set incorrectly. Thanks for that!
So, you glue it to the OS yourself. That's... well actually I guess if someone marries it to SDL it could be very useful.
It's nice because your backend doesn't matter. If I have a custom rendering platform I can probably spit out an image. But if I don't want to write a gui library or hook up some BS like QT, this is a super simple solution. I have three projects for three different clients which can use this, for at least internal debugging.
So, you glue it to the OS yourself. That's... well actually I guess if someone marries it to SDL it could be very useful.