status.i4.v = wn_background_color_c(color.i4.v)

	This routine sets the background color for graphical windows
	created by future calls to wn_view(_c).  If a background
	color other than BLACK is selected, it would be wise to call
	wn_text_attributes_c and set the text drawing mode to
	additive (WN_TEXT_ADDITIVE) so that text background is not
	set to black.

	color		window background color (constants are in 'cnsparam')
			(If a value of CLIB_DEFAULT_ARG is passed for this
			argument, the present background color will simply
			be returned to the caller.) (default is BLACK)

	This function returns status values as follows:

	CBS_INVARG		invalid color
	otherwise		previous background color

	This function requires the following include files:

	cnsparam_h, cbslib_h, acnet_errors_h

	Related functions:

	wn_view(_c), wn_text_attributes_c, intro_graphics_windows

	C/C++ usage:

	int	status;
	int	color = BLACK;

	status = wn_background_color_c(color);