Thanks for the answer, it looked very promising, but unfortunately that doesn't change anything... do_one_event() still waits for a keypress, although the timeout was set to 0 and 1, for testing.

My program works flawlessly when I keep my finger on the arrow-down key for example, but once I stop nothing gets updated anymore, because that damn function doesn't return.

Any other ideas?

If this doesn't work I have to use the backup version of that program, where I wrote the UI handling myself.. badly hacked together, but at least that worked...