| 
            plsdrawmode
          ( | mode ); | 
      Set drawing mode.  Note only one device driver (cairo) currently
      supports this at the moment.  See also plgdrawmode.
    
mode
          (PLINT
            Control variable which species the drawing mode (one of
            PL_DRAWMODE_DEFAULT,
            PL_DRAWMODE_REPLACE, or
            PL_DRAWMODE_XOR) to use.
          
      Redacted form: plsdrawmode(mode)
    
This function is used in example 34.