var NewWin = null;
function WinOpen(url)
{       
        if (!NewWin || NewWin.closed)
        {
                NewWin = LoadWin(url, 'win_poll', 418, 300);
        }else
        {
                NewWin.focus();
        }
}
function LoadWin(url, name, width, height) 
{ 
	var str = "scrollbars,resizable,location,height=" + height + ",innerHeight=" + height + ",width=" + width + ",innerWidth=" + width; 
	if (window.screen) 
	{ 
		var ah = screen.availHeight - 30; 
		var aw = screen.availWidth - 10; 
		var xc = (aw - width) / 2; 
		var yc = (ah - height) / 2; 
		str += ",left=" + xc + ",screenX=" + xc; 
		str += ",top=" + yc + ",screenY=" + yc; 
	}
	return window.open(url, name, str); 
}