+Unlike other implementations, this one checks parameters such as pointers
+to WINDOW structures to ensure they are not null.
+The main reason for providing this behavior is to guard against programmer
+error.
+The standard interface does not provide a way for the library
+to tell an application which of several possible errors were detected.
+Relying on this (or some other) extension will adversely affect the
+portability of curses applications.
+.PP