xfree86 man page for xsynchronize

XSynchronize(3X11)						  XLIB FUNCTIONS						XSynchronize(3X11)

NAME
       XSynchronize, XSetAfterFunction - enable or disable synchronization

SYNTAX
       int (*XSynchronize(Display *display, Bool onoff))();

       int (*XSetAfterFunction(Display *display, int (*procedure)()))();

ARGUMENTS
       display	 Specifies the connection to the X server.

       procedure Specifies the procedure to be called.

       onoff	 Specifies a Boolean value that indicates whether to enable or disable synchronization.

DESCRIPTION
       The XSynchronize function returns the previous after function.  If onoff is True, XSynchronize turns on synchronous behavior.  If onoff is
       False, XSynchronize turns off synchronous behavior.

       The specified procedure is called with only a display pointer.  XSetAfterFunction returns the previous after function.

SEE ALSO
       XSetErrorHandler(3X11)
       Xlib - C Language X Interface

XFree86 							   Version 4.7.0						XSynchronize(3X11)