Error replies not handled by Xlib when xcb owns the queue
Xlib never tells xcb it expects replies for its request. Therefore
xcb_connection->in.pending_replies is never set. Therefore errors are never put into
->in.replies, because condition at
xcb_in.c:306 is never met. Therefore
xcb_wait_for_reply64 will never return the error. So in
_XReply, in the end both
response are null, and Xlib thinks that's a IO error and kill the application, which is undesirable.