code: function ( index ) {
  		if ( typeof index == 'undefined' ) {
  			var count = 0;
  			for (var i = 0; i < this.contentItems.length; ++i)
  				if ( this._isDocked( i ) )
  					count++;
  			return count;
  		}
  		if ( index < this.contentItems.length )
  			return this.contentItems[ index ]._docker && this.contentItems[ index ]._docker.docked;
  	}
docs: Gets docking information
  @private