Windows: Rename a file to start with . causes an error

[jnweiger]

Seen on windows 10, 22H2 with desktop beta 3.0.0.1960

• Connect client to server, wait for initial sync
• open the sync folder of e.g. Personal space in explorer
• add a file there.foo.txt with a few lines of text. The client syncs to the server. OK
• right-click the file -> rename, remove the first 5 characters, so that .foo.txt remains.
• an error appears, the rename fails, and the file reverts to the original name. BAD

• add a new file .foo.txt, add a new folder .foo --> both can be added, but will not sync. A message in the sync log says, hidden file. OK

The rename behavior is inconsistent with the file creation behavior.

Expected behavior:
A rename that causes a file to start with . simply makes it hidden and stops syncing the file.

[TheOneRing]

While the error message is horrible (we were not able to display custom messages, yet) we actively prevent renaming of placeholders to .files.

Dot files are not synced by default (hidden files) so a local rename of a placeholder to a .file would cause a delete on the server.
Which would be much worse than that error message.