jQuery.fn.fadeToggle = function(speed, easing, callback) { 
   return this.animate({opacity: 'toggle'}, speed, easing, callback); 
}; 
$(document).ready(function(){
$("#sidebar ul li").click(
function(){
$(this).siblings().children("ul").hide();
$(this).children("ul").fadeToggle();
}
);
$("#sidebar ul li ul li").hover(
function(){
},
function(){
});
});