function openSubmenu(id)
{
    window.document.getElementById("menu_subitem_"+id).style.visibility = "visible";
}

function closeSubmenu(id)
{
    window.document.getElementById("menu_subitem_"+id).style.visibility = "hidden";
}


function toggleContentOverlay(show)
{
    var overlayElement = window.document.getElementById("navi_content_overlay_div");
    var overlayElementIE6 = window.document.getElementById("navi_content_overlay_div_ie6");

        
	if(show)
	{
		overlayElement.style.display = "block";
		overlayElement.style.visibility = "visible";
        
        if (typeof(isIE6) != 'undefined')
        {
            overlayElementIE6.style.display = "block";
		    overlayElementIE6.style.visibility = "visible";
        } 
        
	}
	
	else if(!show && !explanationOpened)
	{
		overlayElement.style.display = "none";
		overlayElement.style.visibility = "hidden";
        
        if (typeof(isIE6) != 'undefined')
        {
            overlayElementIE6.style.display = "none";
		    overlayElementIE6.style.visibility = "hidden";
        } 
	}
    
        if (typeof(isIE6) != 'undefined') 
        {
            try
            {
                //window.document.getElementById("main_centered_div")
                overlayElement.style.height = window.document.getElementById("main_centered_div").offsetHeight;
                overlayElement.style.width = window.document.getElementById("main_centered_div").offsetWidth;
                
				overlayElementIE6.style.height = window.document.getElementsByTagName("body")[0].offsetHeight;
                overlayElementIE6.style.width = window.document.getElementsByTagName("body")[0].offsetWidth;
			}
			
			catch(Exception)
			{
				overlayElement.style.height = window.document.body.offsetHeight;
                overlayElement.style.width = window.document.body.offsetWidth;

				//overlayElementIE6.style.height = window.document.body.offsetHeight;
                //overlayElementIE6.style.width = window.document.body.offsetWidth;
			}
        }
}