In this section:
This call-back function takes one character string argument and displays it as a yes/no question. It is designed to be used with a button or menu option that will exit a window. If the user responds yes, the function returns zero, thus closing the window with the return number of the original button. If the user responds no (the default response) the window remains open. If a window closure call-back (%cc (Control Closure)) has been specified, the %cc call-back is called before the closure takes place.