DMXSync - flush protocol requests between Xdmx and back-end X servers
Bool DMXSync(Display *dpy);
flushes all pending protocol requests between the
(1) server and each back-end X server. It is used by clients that
talk directly to back-end X servers to ensure that all pending Xdmx
requests have reached all back-end servers and have been processed by those
unless there is a protocol error.