var MenuDropDown = {
	keepAlive : [],
	show: function( menuItem, isSimpleDD ){
		$(menuItem).addClassName(!!isSimpleDD?"ddOver":"menuBtn_over");
		if( !menuItem.isVisible ){
			var div = $(menuItem).select( "div.submenuHolder" )[0];
			if( div ){
				div.observe( "mouseover", this.show.bind(this,menuItem, !!isSimpleDD) );
				div.observe( "mouseout", this.hide.bind(this,menuItem) );
				div.style.height = div.getHeight()+"px";
				div.hide();
				Effect.Appear( div, {duration: 0.3});
			}
		}
		if( menuItem.itemId == undefined || menuItem.itemId == null ){
			menuItem.itemId = this.keepAlive.length;
			this.keepAlive.push(true);
		}
		menuItem.isVisible = true;
		this.keepAlive[menuItem.itemId] = true;
	},
	hide: function( menuItem ){
		var id = menuItem.itemId;
		if( id === undefined )
			return;
		this.keepAlive[id] = false;
		window.setTimeout(this.killSubmenu.bind(this, menuItem), 1000);
	},
	killSubmenu: function(menuItem){
		var id = menuItem.itemId;
		if( id === undefined || this.keepAlive[id] === true )
			return;

		$(menuItem).removeClassName("menuBtn_over");
		$(menuItem).removeClassName("ddOver");
		menuItem.isVisible = false;
	}
};