message: Don't allow drag on other section in Timeline (mac)
diff: @@ -454,6 +454,12 @@ extension TimelineDatasource {
  func collectionView(_ collectionView: NSCollectionView, validateDrop draggingInfo: NSDraggingInfo, proposedIndexPath proposedDropIndexPath: AutoreleasingUnsafeMutablePointer<NSIndexPath>, dropOperation proposedDropOperation: UnsafeMutablePointer<NSCollectionView.DropOperation>) -> NSDragOperation {
  print("validate drop at \(proposedDropIndexPath.pointee), operation = \(proposedDropOperation.pointee)")
  + let dropIndexPath = proposedDropIndexPath.pointee
  +
  + // Only allow drop in the Time Entry section
  + guard dropIndexPath.section == TimelineData.Section.timeEntry.rawValue else {
  + return []
  + }
  // Don't allow to drop on top of others
  if proposedDropOperation.pointee == .on {
  