What UI APIs are there that don't have a concept of UI thread(s)? Coming from Windows, I'm used to UI work needing to be done on a UI thread.

I randomly googled these comments:

"Never, ever, touch the UI from outside your UI thread, in any version of Qt."

"Android UI toolkit is not thread-safe and must always be manipulated on the UI thread."

google "iOS 'non-UI thread'": 60 million results.

javascript: everything UI-related runs on one thread.

Do you do much UI coding?