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 1.1.5.2 XtName(3)