https://manpages.ubuntu.com/manpages/xenial/man3/XmTextFieldPosToXY.3.html
Ubuntu Manpage: XmTextFieldPosToXY - A TextField function that accesses the x and y position of a...
A TextField function that accesses the x and y position of a character position "XmTextFieldPosToXY" "TextField functions" "XmTextFieldPosToXY"