function menuaction(id, action){
		sub_id = 'sub' + id;
		prefix_id = 'prefix' + id;
		if(document.getElementById(sub_id)){
			menu_pic_path = '/img/treemenu/';
			submenu = $(sub_id);
			prefix = $(prefix_id);
			
			if(action == null){
				if(!submenu.visible()){
					new Effect.SlideDown(submenu, { queue: { position: 'end', scope: 'menuxscope', limit: 2 }, duration: 0.2 });
					prefix.setStyle({backgroundImage: 'url('+menu_pic_path+'minus.gif)'});
				}else{
					new Effect.SlideUp(submenu, { queue: { position: 'end', scope: 'menuxscope', limit: 2 }, duration: 0.2 });
					prefix.setStyle({backgroundImage: 'url('+menu_pic_path+'plus.gif)'});
				}
			}else{
				if(action == 'expand' && !submenu.visible()){
					submenu.slideDown({duration: 0.3});
					prefix.setStyle({backgroundImage: 'url('+menu_pic_path+'minus.gif)'});
				}else if(action == 'contract' && submenu.visible()){
					submenu.slideUp({duration: 0.3});
					prefix.setStyle({backgroundImage: 'url('+menu_pic_path+'plus.gif)'});
				}
			}
		}
	}