function popupWin(url, w, h, scroll){
	if(!w) w = 500;
	if(!h) h = 500;
	var x = screen.availWidth /2 - ( w /2 );
	var y = screen.availHeight /2 - ( h /2 );
	window.open( url, 'popupWin', 'width=' + w + ',height=' + h + ',screenY=' + y + ',screenX='+ x + ',top=' + y + ',left=' + x + ',scrollbars=' + scroll );
}