function winopen(url,tar,w,h)
{
	if (w==0)
	{
		w=600;
	}
	if (h==0)
	{
		h=400;
	}
	var l=(screen.width-w)/2;
	var t=(screen.height-h)/2-30;
	window.open(url,tar,"location=no,scrollbars=yes,menubars=no,toolbars=no,resizable=no,left="+l+",top="+t+",width="+w+",height="+h);
	return false;
}