function openWindow(mapage,width,height) 
{
        x = (640 - width)/2, y = (480 - height)/2;
        
		if (screen) 
		{
			y = (screen.availHeight - height)/2;
			x = (screen.availWidth - width)/2;
        }
		
        if (screen.availWidth > 1800) 
		{
			x = ((screen.availWidth/2) - width)/2;
        }
		
        window.open(mapage,'','scrollbars=no,resizable=no,width='+width+',height='+height+',screenX='+x+',screenY='+y+',top='+y+',left='+x);
}