function mouseIn(menuNum) {
    	// create an iframe at the exact same position and size as the sub div
	    var shimmer = document.getElementById('shimmer');
    	var md = document.getElementById('maindiv' + menuNum);
    	var sd = document.getElementById('navdetails' + menuNum);
				
    	// dimensions and position of iframe
	    shimmer.style.position='absolute';
    	shimmer.style.height = '0px';
    	shimmer.style.width = '0px';
    	shimmer.style.zIndex='1010';
	    shimmer.style.display='block';
    	//add .navHover class 
    	md.className='navHover';
    	
		// make sub div visible
    	sd.style.visibility='visible';
    	sd.style.display='block';
    	sd.style.zIndex = '1020';

    	mdHeightOffset = md.offsetTop + md.offsetHeight;
    	
    	sd.style.top  = mdHeightOffset + 'px';
    	sd.style.left = md.offsetLeft + 'px';
    	shimmer.style.top  = mdHeightOffset + 'px';
    	shimmer.style.left = sd.offsetLeft + 'px';
    	shimmer.style.height = sd.offsetHeight + 'px';
    	shimmer.style.width = sd.offsetWidth + 'px';
    }
	
	//remove iframe and className 'navHover'
    function mouseOut(menuNum) {
    	var md = document.getElementById('maindiv' + menuNum);
    	var sd = document.getElementById('navdetails' + menuNum);
	    var shimmer = document.getElementById('shimmer');

        sd.style.visibility='hidden';
        md.className='';
        shimmer.style.display='none';
    }