https://invisible-island.net/xterm/xtoolkit/
XtAppAddWorkProc, XtRemoveWorkProc - Add and remove background process-
ing procedures
#include <X11/Intrinsic.h>
XtWorkProcId XtAppAddWorkProc(XtAppContext app_context, XtWorkProc
proc, XtPointer client_data);
void XtRemoveWorkProc(XtWorkProcId id);
app_context
Specifies the application context that identifies the appli-
cation.
client_data
Specifies the argument that is to be passed to the specified
procedure when it is called.
proc Specifies the procedure that is to be called.
id Specifies which work procedure to remove.
The XtAppAddWorkProc function adds the specified work procedure for the
application identified by app_context.
The XtRemoveWorkProc function explicitly removes the specified back-
ground work procedure.
XtAppNextEvent(3)
X Toolkit Intrinsics - C Language Interface
Xlib - C Language X Interface
X Version 11 libXt 1.3.1 XtAppAddWorkProc(3)