wn_insrow -- insert row in window

        USAGE

          wn_insrow(wn, row)
          WINDOWPTR wn;
          int row;

                wn -  window handle
                row - row at which a line is to be inserted

          Row is relative to the origin of the window.  All lines below
          the row specified are scrolled down.  The currently defined
          window attribute is used to clear the lines inserted.

        RETURNS

          TRUE or NULL if error

        CAUTIONS

          The window "wn" automatically becomes the top window tile upon
          return.