function popupWindow(popupLocation, windowName, popupWidth, popupHeight) {
		var leftdist 	= (screen.width - popupWidth) / 2;    	// distance to left edge of window
		var topdist 	= (screen.height - popupHeight) / 2;   	// distance to top edge of window
		var popUpWin = window.open(popupLocation, windowName, "left=" + leftdist + ",top=" + topdist + ",width=" + popupWidth + ",height=" + popupHeight + ",scrollbars=no");
	}