window_exists_c

	status.i4.v = window_exists_c(window_id.i2.v)

	This routine will return a value of TRUE if the requested
	window presently exists and a value of FALSE otherwise.

	window_id	window ID (use WMNGR_BACKGROUND for background window)

	This function returns status values as follows:

	TRUE			window presently exists
	FALSE			window does not exist

	This function requires the following include files:

	cnsparam_h, cbslib_h

	Related functions:

	window_construct(_c), window_create(_c), window_delete(_c),
	intro_tv_windows

	C/C++ usage:

	short	window_id;

	if (window_exists_c(window_id))
	    {
	    }