XGrabServer, XUngrabServer - grab the server
Specifies the connection to the X server.
The XGrabServer function disables processing of requests and close downs on all other connections than the one this request arrived on. You should not grab the X server any more than is absolutely necessary.
function restarts processing of
requests and close downs on other connections. You should avoid grabbing the
X server as much as possible.
XGrabButton(3X11), XGrabKey(3X11), XGrabKeyboard(3X11), XGrabPointer(3X11)
Xlib -- C Language X Interface