function tab1()	{
      var tab1 = document.getElementById('tab1').style;
      var tab2 = document.getElementById('tab2').style;
      var tab3 = document.getElementById('tab3').style;
      var tab4 = document.getElementById('tab4').style;
      tab1.zIndex = 3;
      tab2.zIndex = 1;
      tab3.zIndex = 1;
      tab4.zIndex = 1;
      document.getElementById('pane1').style.visibility = "visible";
      document.getElementById('pane2').style.visibility = "hidden";
      document.getElementById('pane3').style.visibility = "hidden";
      document.getElementById('pane4').style.visibility = "hidden";
      document.getElementById('pane1').style.position = "relative";
      document.getElementById('pane2').style.position = "absolute";
      document.getElementById('pane3').style.position = "absolute";
      document.getElementById('pane4').style.position = "absolute";
    }
    function tab2()	{
      var tab1 = document.getElementById('tab1').style;
      var tab2 = document.getElementById('tab2').style;
      var tab3 = document.getElementById('tab3').style;
      var tab4 = document.getElementById('tab4').style;
      tab1.zIndex = 1;
      tab2.zIndex = 3;
      tab3.zIndex = 1;
      tab4.zIndex = 1;
      document.getElementById('pane1').style.visibility = "hidden";
      document.getElementById('pane2').style.visibility = "visible";
      document.getElementById('pane3').style.visibility = "hidden";
      document.getElementById('pane4').style.visibility = "hidden";
      document.getElementById('pane1').style.position = "absolute";
      document.getElementById('pane2').style.position = "relative";
      document.getElementById('pane3').style.position = "absolute";
      document.getElementById('pane4').style.position = "absolute";
    }
    function tab3()	{
      var tab1 = document.getElementById('tab1').style;
      var tab2 = document.getElementById('tab2').style;
      var tab3 = document.getElementById('tab3').style;
      var tab4 = document.getElementById('tab4').style;
      tab1.zIndex = 1;
      tab2.zIndex = 1;
      tab3.zIndex = 3;
      tab4.zIndex = 1;
      document.getElementById('pane1').style.visibility = "hidden";
      document.getElementById('pane2').style.visibility = "hidden";
      document.getElementById('pane3').style.visibility = "visible";
      document.getElementById('pane4').style.visibility = "hidden";
      document.getElementById('pane1').style.position = "absolute";
      document.getElementById('pane2').style.position = "absolute";
      document.getElementById('pane3').style.position = "relative";
      document.getElementById('pane4').style.position = "absolute";
    }
    function tab4()	{
      var tab1 = document.getElementById('tab1').style;
      var tab2 = document.getElementById('tab2').style;
      var tab3 = document.getElementById('tab3').style;
      var tab4 = document.getElementById('tab4').style;
      tab1.zIndex = 1;
      tab2.zIndex = 1;
      tab3.zIndex = 1;
      tab4.zIndex = 3;
      document.getElementById('pane1').style.visibility = "hidden";
      document.getElementById('pane2').style.visibility = "hidden";
      document.getElementById('pane3').style.visibility = "hidden";
      document.getElementById('pane4').style.visibility = "visible";
      document.getElementById('pane1').style.position = "absolute";
      document.getElementById('pane2').style.position = "absolute";
      document.getElementById('pane3').style.position = "absolute";
      document.getElementById('pane4').style.position = "relative";
    }