function openwincenter(target,wid,hei) {
var scw = screen.width;
var sch = screen.height;
wid = wid + 20;
hei = hei + 25;
x = ((scw - wid) / 2);
y = ((sch - hei) / 2);
val = "width="+wid+",height="+hei+",status=no,scrollbars=yes,resizable=no,left="+x+",top="+y;
window.open("",target,val);
}