window.onload = init;
var dyingMenu = new Object();
function init ( ) {
  var topMenu = document.getElementById( 'top_menu' );
  for ( var i = 0; i < topMenu.childNodes.length; i++ ) {
    topMenu.childNodes[i].onmouseover = function(){killMenu();this.className='show'};
    topMenu.childNodes[i].onmouseout = function(){killMenu(this);setTimeout('killMenu()',500)};
  }
}
function killMenu ( currentElement ) {
  if ( dyingMenu.menu && dyingMenu.menu != currentElement ) dyingMenu.menu.className = '';
  dyingMenu.menu = currentElement;
}