did_it.i4.v = window_change_case_c(window_id.i2.v, row.i4.v,
					   column.i4.v, num_chars.i4.v)

	This routine changes (inverts) the case of characters in a window.

	window_id	window ID (use WMNGR_BACKGROUND for background window)
	row		window row
	column		starting column
	num_chars	number of characters

	This function returns status values as follows:

	CBS_MEMFAIL		dynamic memory allocation failure
	TRUE			window I/O actually done
	FALSE			no window I/O done

	This function requires the following include files:

	cnsparam_h, cbslib_h, acnet_errors_h

	Related functions:

	window_up_case_c, window_down_case_c, window_tvm(_c), window_tvmx(_c),
	window_read_color_text_c, intro_tv_windows

	C/C++ usage:

	short	window_id;
	int	did_it;
	int	row = 1;
	int	column = 1;
	int	num_chars = 10;

	did_it = window_change_case_c(window_id,row,column,num_chars);