File replacement dialogue might block file getting overwritten
A note to start with, files opened on an SMB share cannot be deleted until they're closed.
- Copy a large file that can be thumbnailed to an SMB share, such as a big PDF, in a sub-directory so that it isn't thumbnailed
- Copy the file again into that sub-directory
- You will get the "replace file" dialogue, which will try to generate the thumbnail for the file that's about to be overwritten
- Click "Replace" quickly enough that the thumbnail hasn't had time to be generated
- Get an error as it tries to replace a file that's still opened by the thumbnailer
The thumbnail API currently doesn't have a way to cancel thumbnails, but this is a place where it would be useful to use that.