extract_backcolor

	EXTRACT_BACKCOLOR(color)

	This macro returns the background color code from a color value
	suitable for passing to "window_" routines and the "wn_" routines
	wn_display_value(_c), wn_colored_text_c,
	wn_external_display_value_c, and wn_external_colored_text_c.

	color		compound color value

	This macro returns values as follows:

	extracted background color

	This macro is found in: macro_h

	Related macros:

	tv_colors, TV_COLORS_WBLINK, EXTRACT_FORECOLOR, EXTRACT_BLINK,
	INVERT_COLORS, BLINK_COLOR