function toggle(submenu) {
if (document.getElementById("submenu"+submenu).style.display == "none")
{
 document.getElementById("submenu"+submenu).style.display = "block";
  document.getElementById("mainmenu"+submenu).style.background="url(/files/str2.gif) no-repeat 3px";
}
 else if (document.getElementById("submenu"+submenu).style.display == "block")
{ 
 document.getElementById("submenu"+submenu).style.display = "none";
 document.getElementById("mainmenu"+submenu).style.background="url(/files/str1.gif) no-repeat 3px";
} 
}