https://invisible-island.net/xterm/xtoolkit/
XtCallAcceptFocus - calla widget's accept_focus procedure
#include <X11/Intrinsic.h>
Boolean XtCallAcceptFocus(Widget w, Time *time);
time Specifies the X time of the event that is causing the accept
focus.
w Specifies the widget.
The XtCallAcceptFocus function calls the specified widget's accept_fo-
cus procedure, passing it the specified widget and time, and returns
what the accept_focus procedure returns. If accept_focus is NULL,
XtCallAcceptFocus returns False.
XtSetKeyboardFocus(3)
X Toolkit Intrinsics - C Language Interface
Xlib - C Language X Interface
X Version 11 libXt 1.3.1 XtCallAcceptFocus(3)