While testing some recent code for the excellent DropBox support that @fredericjb added I found a pre-existing issue related to folder watchers. If the folder being watched goes away, the poller will correctly shut down and turn the folder icon red on the GUI. For example if a folder is configured on a network share or DropBox and the network goes away or if a local folder is renamed. This is what I would expect to happen. The issue is that the folder never returns when it becomes available in some cases. If the folder is on Dropbox or is renamed, then it will never return. If the folder is on a network share (mapped drive), then it will return when the mapped drive returns.
There is logic to detect the introduction of a FileSystem change, and if there is any FileSystem change, it will try to refresh the folder. In the case of a mapped drive, a new drive letter is added (talking Windows here) and a rescan occurs. In the case of a folder rename or Dropbox, then it never comes back.
It's not clear whether this is a bug or just a missing feature, but the fact that it works with one file system type but not another was why I classified it here. The workaround is trivial, just hit the stop/start button and you're back up and running.
Version: 23.5.0 Failed to create the part's controls
You should create/comment bugs in https://github.com/mytourbook/mytourbook/issues
I thought that I had prevented, that a comment cannot be created in sourceforge. Now I adjusted the permissions again.