log where the user change the item. If not implemented, nothing happens.</li>
    <li><code>onDropObjectOnItem(objectData, item)</code> Fired when an object is dropped in to an existing timeline item.</li>
    <li><code>onMove(item, callback)</code> Fired when an item has been moved. If not implemented, the move action will be accepted.</li>
    <li><code>onMoving(item, callback)</code> Fired repeatedly while an item is being moved (dragged). Can be used to adjust the items start, end, and/or group to allow