https://invisible-island.net/xterm/xtoolkit/
XtName - obtain widget's name
#include <X11/Intrinsic.h>
String XtName(Widget w);
w Specifies the widget.
XtName returns the widget's name.
X Toolkit Intrinsics - C Language Interface
Xlib - C Language X Interface
X Version 11 libXt 1.3.1 XtName(3)