XSetEventQueueOwner - set event queue owner on a shared Xlib/XCB connection
   #include <X11/Xlib-xcb.h>
void XSetEventQueueOwner(Display *dpy, enum
    XEventQueueOwner owner);
  - dpy
- Specifies the connection to the X server.
- owner
- Specifies the event queue ownership:
  - XlibOwnsEventQueue (default)
- Xlib owns the event queue. Use the Xlib event-handling functions. Do not
      call the XCB event-handling functions.
- XCBOwnsEventQueue
- XCB owns the event queue. Use the XCB event-handling functions. Do not
      call the Xlib event-handling functions.
 
While a client using Xlib/XCB can issue requests and handle their replies or
  errors with either Xlib or XCB, only one can own and handle the event queue.
  By default, Xlib must own the event queue, for compatibility with legacy Xlib
  clients. Clients can call XSetEventQueueOwner immediately after
  XOpenDisplay to let XCB own the event queue instead. Clients may not
  call XSetEventQueueOwner at any other time, as this will potentially
  lose responses.
XOpenDisplay(3), XGetXCBConnection(3),
Xlib - C Language X Interface