var hWin = null;

var sw = 800;
var sh = 600;
	
function openWin(url, ww, wh) {
	if (screen.width)  sw = screen.width;
	if (screen.height) sh = screen.height;

  hWin = window.open(url, 'openWin_Popup', 'scrollbars=yes,width=' + ww + ',height=' + wh + ',left=' + ((sw - ww) / 2) + ',top=' + ((sh - wh) / 2));
    
 	if (hWin) hWin.focus();
}