var timeout         = 500;
      var closetimer		= 0;
      var ddmenuitem      = 0;
      
      // open hidden layer
      function mopen(id)
      {	
	  	// cancel close timer
      	mcancelclosetime();
      
      	// close old layer
     	if(ddmenuitem) ddmenuitem.style.display = 'none';
      
      	// get new layer and show it
      	ddmenuitem = document.getElementById(id);
      	ddmenuitem.style.display = 'block';
	  }
      	// close showed layer
      	function mclose()
      	{
      		if(ddmenuitem) ddmenuitem.style.display = 'none';
      	}
      
      	// go close timer
      	function mclosetime()
      	{
        	closetimer = window.setTimeout(mclose, timeout);
      	}
      
      // cancel close timer
      function mcancelclosetime()
      {
      		if(closetimer)
      		{
      			window.clearTimeout(closetimer);
      			closetimer = null;
      		}
      }
      
      // close layer when click-out
      document.onclick = mclose;