I recently came across similar behaviour in Linux - if you are waiting in XNextEvent on one thread and you call glXSwapBuffers on another, it never returns. If

I recently came across similar behaviour in Linux - if you are waiting in XNextEvent on one thread and you call glXSwapBuffers on another, it never returns. If you move the mouse, XNextEvent returns with a MotionNotify event and glXSwapBuffers can grab some internal X11 lock and complete. It then gets stuck on the next frame. The result is that you have to keep moving the mouse or nothing is drawn. X11 is supposed to be multithreaded enough to allow this and it worked fine on older versions of Xlib, before the libxcb transition. Fixed by using select() in the event loop for the curious: https://github.com/lcrs/6ilk/commit/d5c39abde09e0467a8a4d17d973e8d89c7fd4fab#diff-729da247b80ee74140a7732c42a735c3R125 https://github.com/lcrs/6ilk/commit/d5c39abde09e0467a8a4d17d...