function listClose()
{
      document.getElementById("selectbox_list").style.display = "none"; 
      document.getElementById("selectbox_value").style.backgroundPosition = "right 0px";  
}
function listOpen()
{
      document.getElementById("selectbox_value").focus();
      document.getElementById("selectbox_list").style.display = "block";
      document.getElementById("selectbox_value").style.backgroundPosition = "right -20px";  
}
function listToggle()
{
   if(document.getElementById("selectbox_list").style.display == "block")
   {
       listClose();
   }
   else
   {
       listOpen()
   }
}