is_exposed.i4.v = window_exposed_region_c(window_id.i2.v, top_row.i4.v,

	This routine returns a value of FALSE if the requested region in
	the window indicated by "window_id" is occluded (either partially or
	completely) by another window.

	window_id	window ID (use WMNGR_BACKGROUND for background window)
	top_row		top row of region in full screen coordinates
	num_rows	number of rows
	left_column	left column of field in full screen coordinates
	num_columns	number of columns

	This function returns status values as follows:

	TRUE			region is exposed
	FALSE			region is occluded

	This function requires the following include files:

	cnsparam_h, cbslib_h

	Related functions:

	window_gap_c, window_gap_length_c, window_hole_c,
	screen_row(_c), screen_column(_c), in_window_box(_c), intro_tv_windows

	C/C++ usage:

	short	window_id;
	int	is_exposed;
	int	top_row = 1;
	int	num_rows = 2;
	int	left_column = 1;
	int	num_columns = 10;

	top_row = screen_row_c(window_id,top_row);
	left_column = screen_column_c(window_id,left_column);

	is_exposed = window_exposed_region_c(window_id,top_row,num_rows,