function window_open(url,winName,width,height)
{
	xpos = (screen.width-width)/2;
	ypos = (screen.height-height)/2;
	options = "scrollbars=1,width="+width+",height="+height+",left="+xpos+",top="+ypos+"position:absolute";
	window.open(url,winName,options);
}