newWindow = null;
 function makeWindow(name,w,h,x,y)
 {
   zu();
   newWindow = window.open(name,"_blank","scrollbars=yes,resizable=yes,width=" + w + ",height=" + h +",screenX="+x+",screenY="+y )
 }

 function zu()
 {
   if (newWindow != null)
     if (!newWindow.closed)
       newWindow.close();
 }