public function bind( $key, $callback ){
		if( is_callable( $callback ) )
			$callback	= new ADT_Event_Callback( $callback );
		if( !( $callback instanceof ADT_Event_Callback ) )
			throw new InvalidArgumentException( 'Callback must be function or instance of ADT_Event_Callback' );
		if( !is_array( $list = $this->events->get( $key ) ) )
			$list	= array();
		$list[]	= array( $key, $callback );
		$this->events->set( $key, $list );
	}