Previously we relied on the application to send all X events through
Cogl using cogl_xlib_renderer_handle_event. This breaks the
abstraction that an application shouldn't need to know what winsys
Cogl is using. Now that we have main loop integreation in Cogl, the
Xlib-based winsys's can report that Cogl needs to block on the file
descriptor of the X connection and it can manually handle the
events.
The event retrieval can be disabled by an application if it calls the
new cogl_xlib_renderer_set_event_retrieval_enabled() function. The
event retrieval will also automatically be disabled if the application
sets a foreign display.
Reviewed-by: Robert Bragg <robert@linux.intel.com>