function displayMenu(a, obj) {
		    var menu = document.getElementById(obj);	  
				var lin = document.getElementById(a);
				
		    if(menu.style.display == "none") {
		    			menu.style.display = "block";
		    			lin.style.backgroundImage = "url(images/index_03_hover.png)";
		    }	else {
		    			menu.style.display = "none";
		    			lin.style.backgroundImage = "none";
		    } 
}