+ X/Open defines no error conditions. In this implementa-
+ tion
+
+ <STRONG>delwin</STRONG>
+ returns an error if the window pointer is
+ null, or if the window is the parent of anoth-
+ er window.
+
+ This implementation also maintains a list of
+ windows, and checks that the pointer passed to
+ <STRONG>delwin</STRONG> is one that it created, returning an
+ error if it was not..
+
+ <STRONG>mvderwin</STRONG>
+ returns an error if the window pointer is
+ null, or if some part of the window would be
+ placed off-screen.
+
+ <STRONG>mvwin</STRONG>
+ returns an error if the window pointer is
+ null, or if the window is really a pad, or if
+ some part of the window would be placed off-
+ screen.
+
+ <STRONG>syncok</STRONG>
+ returns an error if the window pointer is
+ null.
+