var iMousePosX;
var fNetscape = false;
function init()
{ fNetscape = navigator.appName == "Netscape";
  if( fNetscape )
  { document.captureEvents(Event.MOUSEMOVE);
    document.onmousemove = watch_mouse;
  }
}
function watch_mouse(e)
{ iMousePosX = e.clientX;
}
var popup_window = null;
function openPopup(url)
{ if(popup_window != null)
    popup_window.focus();
  else
  { var width = (screen.width/2) *0.9;
    var height = screen.height *0.9;
    var extra = (screen.width/2) *0.05;
    var left;
    if( !fNetscape )
      iMousePosX = event.screenX;
    if( iMousePosX < (screen.width/2) )
      left = screen.width/2 + extra;
    else
      left = screen.width/2 - width - extra;
    popup_window = open(url, "Popup", "width=" +width+ ",height=" +height+ ",left="+ left+ ", top=0");
  }
}
function closePopup()
{ if(popup_window != null)
  { popup_window.close();
    popup_window = null;
  }
}