wn_natrib -- set new attribute in window NOW!

        USAGE

          wn_natrib(wn,atrib)
          WINDOWPTR wn;
          int atrib;

            wn    - window handle
            atrib - attribute to set the window specified by wn to.

          The attributes of the window are changed immediately.

          Attributes are defined in window.h

          The border is not altered.

        RETURNS

          TRUE or NULL if error

        CAUTIONS

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