XmStringExtent - A compound string function that determines the size of the smallest rectangle that will enclose the compound string
#include <Xm/Xm.h>
void XmStringExtent (fontlist, string, width, height)
XmFontList fontlist;
XmString string;
Dimension *width;
Dimension *height;
XmStringExtent determines the width and height, in pixels, of the smallest rectangle that will enclose the provided compound string.