var timeout	= 300; 
var closetimer	= 0; 
var ddmenuitem	= 0; 

// open hidden layer 

function mopen(id) {	 

// cancel close timer 
mcancelclosetime(); 

// close old layer 
if (ddmenuitem) ddmenuitem.style.visibility = 'hidden'; 

// get new layer and show it 
ddmenuitem = document.getElementById(id); ddmenuitem.style.visibility = 'visible'; } 

// close showed layer 

function mclose() { 

if(ddmenuitem) ddmenuitem.style.visibility = 'hidden'; 
} 

// go close timer 

function mclosetime() { 
closetimer = window.setTimeout(mclose, timeout); 
} 
// cancel close timer 
function mcancelclosetime() { 
if(closetimer) { 
window.clearTimeout(closetimer); closetimer = null; 
} 
} 
// activate nav on tab 
function navOn(menuId) { 
document.getElementById(menuId).className="menuOn" 
}
function navOff(menuId) { 

document.getElementById(menuId).className="menuOff" 
} 
// close layer when click-out
document.onclick = mclose;