var winhandle = null;

function popUp(aURL, aWidth, aHeight) {
  if ((winhandle != null) && (! winhandle.closed)){

    winhandle.resizeTo(aWidth, aHeight);
    winhandle.location.replace(aURL);

  }
  else
  {
    winhandle=window.open(aURL, "imagewin", 'width=' + eval(aWidth) + ',height=' + eval(aHeight) + ',resizable,scrollbars');
  }

  winhandle.focus();

}