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)