+.PP
+X/Open Curses states regarding \fBdelwin\fP:
+.bP
+It must delete subwindows before deleting their parent.
+.bP
+If \fBdelwin\fP is asked to delete a parent window,
+it can only succeed if the curses library keeps a list of the subwindows.
+SVr4 curses kept a count of the number of subwindows rather than a list.
+It simply returned \fBERR\fP when asked to delete a subwindow.
+Solaris X/Open curses does not even make that check,
+and will delete a parent window which still has subwindows.
+.bP
+Since release 4.0 (1996), ncurses maintains a list of windows for each screen,
+and is able to recursively delete subwindows when asked to delete their parent.
+.bP
+NetBSD copied this feature of ncurses in 2003.
+.br
+PDCurses follows the scheme used in Solaris X/Open curses.