occluded.i4.v = window_occluded_c(window_id.i2.v)

	This routine returns a value of TRUE if the window indicated by
	"window_id" is (partially or completely) occluded.  If a nonexistent
	window is requested, a value of TRUE is returned.

	window_id	window ID (use WMNGR_BACKGROUND for background window)

	This function returns status values as follows:

	TRUE			window is occluded
	FALSE			window is exposed

	This function requires the following include files:

	cnsparam_h, cbslib_h

	Related functions:

	window_occluded_by_c, window_occluding_c, window_is_occluding_c,
	window_intersect_c, intro_tv_windows

	C/C++ usage:

	short	window_id;
	int	occluded;

	occluded = window_occluded_c(window_id);