function popup(theLink)
   {
      var screen_height = screen.height;
      var screen_width = screen.width;
      if (screen_height >= 768){
         var w = 800;
         var h = 600;
      }else{
         var w = 600;
         var h = 500;
      }
      var LeftPosition=(screen.width)?(screen.width-w)/2:100;
      var TopPosition=(screen.height)?(screen.height-h)/2:100;
      win=window.open(theLink,'',"resizable=yes, top=" + TopPosition + ", left=" + LeftPosition + ",width=" + w + ",height=" + h + ",scrollbars=yes");
   }