I don’t know whether this is a Linux specific issue or not, but it seems pretty major.
I have a small app which uses a background thread for midi playback, and a regular DialogWindow with some play, pause buttons and a slider for seeking.
The playback thread is a ChangeBroadcaster which sends messages a few times a second to signal playback progress. When the message is received, the UI queries the current position from the playback thread to update the seeking slider.
However, none of the UI messages are being triggered, and the UI is not being updated, unless I continuously move the mouse pointer over the window. Some debug printf’s confirm that messages are not being processed otherwise.