var arrayHolder = new Array(3);
    arrayHolder[0] = "panel1";
    arrayHolder[1] = "panel2";
    arrayHolder[2] = "panel3";
    arrayHolder[3] = "panel4";

    
     function show_mouseover(id) 
     {   
         hideall();
         showdiv(id);    
     }
 
      function hideall()
      {
          var loopcounter = arrayHolder.length; 
          for (i=0;i<=loopcounter-1;i++)
          {

              document.getElementById(arrayHolder[i]).style.display = 'none';
              document.getElementById(arrayHolder[i]).style.visibility = 'hidden';

          }
      }
      
      function showdiv(id)
      {

      var arrayval = arrayHolder[eval(id)];
     
      var e = document.getElementById(arrayval);
      e.style.display = 'block';
      e.style.visibility = 'visible';
      }