[overgard]

Immediate mode, if anything, makes this harder. (You absolutely have to run the GUI on one thread, for instance). Really though you can get around that on either of them by spawning a worker thread/coroutine/etc. on button clicks and so on.

[weinzierl]

The real problems start, when the worker thread needs to update the GUI, for example to advance a progress bar. With the frameworks I know I have to build a communication channel between the threads and tell the GUI thread to show and update the progress bar.

My hope was that with an immediate mode framework I could just show a progress bar on top of the existing GUI right from the worker thread. I don't know enough about immediate mode to say if this is really possible. It would simplify a lot of my code though.