status.i4.v = wn_draw_mode(draw_mode.i4.r)

	status.i4.v = wn_draw_mode_c(draw_mode.i4.v)

	This routine sets the current drawing mode for the "wn_xxx"
	graphical routines.

	draw_mode	pixel drawing mode
			(WN_REPLACE ->	replace mode (default),
			 WN_OR -> "or" mode,
			 WN_AND -> "and" mode,
			 WN_XOR -> exclusive "or" mode,
			 CLIB_DEFAULT_ARG -> simply return the present
					     drawing mode)

	This function returns status values as follows:

	CBS_INVARG		invalid mode
	otherwise		previous drawing mode

	This function requires the following include files:

	clib_h, cbslib_h, acnet_errors_h

	Related functions:

	wn_point(_c), wn_box(_c), wn_circle(_c), wn_circular_arc_c, wn_text(_c),

	C/C++ usage:

	int	status;
	int	draw_mode = WN_REPLACE;

	status = wn_draw_mode_c(draw_mode);