Getting the Popup to the center of the page for all multiple clicks

Hi,

I have a problem in bringing popup to the center of the page.

It's not a modal popup.

I have used var left = (screen.width - width)/2;
var top = (screen.height - height)/2;

first when user clicks a link , pop up will open on center of the page.

Now user moves this popup to to the left side of the page.

and Once again user clicks on link which opens existing popup but now this popup is not coming to the center it remains on the left side.

So whereever it is being moved it should appear on center of the page for user multiple clicks.

Note: all multiple clicks opens only one popup

please help me ..it is urgent

Thanks
PRas

 

var left = (screen.width - width)/2;
var top = (screen.height - height)/2;
popUpObj.moveTo(left,top);

MoveTo() works for me to force the window.

Thanks