+ * If the destroyed window has the highest window ID number, decrement
+ * the window ID number.
+ *
+ * XXX Do we REALLY want to *ever* recycle window IDs? Integers are
+ * XXX plentiful, and clients may rely upon the implied promise in
+ * XXX the GLUT docs to not recycle these. (I can't remember if it
+ * XXX is explicit.)
+ *
+ * XXX If we *do* want to do this, we should actually recompute the
+ * XXX highest window-ID; the new highest may not in fact be one less
+ * XXX than what we have just deleted.