XtAppAddWorkProc(), XtRemoveWorkProc() - Add and remove background processing procedures
XtWorkProcId XtAppAddWorkProc (XtAppContext app_context, XtWorkProc proc,
XtPointer client_data )
void XtRemoveWorkProc (XtWorkProcId id)
The XtAppAddWorkProc(3) function adds the specified work procedure for the application identified by app_context.
The XtRemoveWorkProc(3) function explicitly removes the specified background work procedure.
X Toolkit Intrinsics - C Language Interface
Xlib - C Language X Interface