prev_clip.i4.v = wn_clip(clipit.i4.r)

	prev_clip.i4.v = wn_clip_c(clipit.i4.v)

	This routine sets the graphic clipping limits to the active graphics
	window if "clipit" is TRUE.  Otherwise, the graphic limits are set to
	the entire screen.

	clipit		clipping flag
			(TRUE -> clip output to the active window,
			 FALSE -> don't clip output,
			 CLIB_DEFAULT_ARG -> simply return the present
					     clipping state)

	This function returns status values as follows:

	TRUE			clipping was previously enabled
	FALSE			clipping was previously disabled

	This function requires the following include files:

	cnsparam_h, cbslib_h

	Related functions:

	wn_box(_c), wn_circle(_c), wn_vector(_c), wn_text(_c), wn_point(_c),
	wn_circular_arc_c, wn_display_value(_c), intro_graphics_windows

	C/C++ usage:

	int	prev_clip;
	int	clipit = TRUE;

	prev_clip = wn_clip_c(clipit);