This implementation of <code>dragOperationChanged</code> permits the default
operation defined in <code>event.detail</code>to be performed on the current data type
defined in <code>event.currentDataType</code>.
For additional information see <code>DropTargetListener.dragOperationChanged</code>.
@param event the information associated with the drag operation changed event
This implementation of <code>dragOperationChanged</code> permits the default operation defined in <code>event.detail</code>to be performed on the current data type defined in <code>event.currentDataType</code>. For additional information see <code>DropTargetListener.dragOperationChanged</code>.
@param event the information associated with the drag operation changed event