These functions extract the complex character and rendi-
tion from the current position in the named window into
the cchar_t object referenced by wcval.
No errors are defined in the XSI Curses standard. This
implementation checks for null pointers, returns ERR in
that case. Also, the mv routines check for error moving
the cursor, returning ERR in that case. Otherwise they
return OK
+ Functions with a "mv" prefix first perform a cursor move-
+ ment using wmove, and return an error if the position is
+ outside the window, or if the window pointer is null.
+