I did some more testing inside Alt+F5:
1. No dirs. If there is a single file and it's deleted, the .ZIP file is also deleted.
2. No dirs. If there are 2 or more files and they are Ctrl+Deleted, the .ZIP file is
declared "empty", but not deleted. Files can then be added to this empty archive.
[Opening and empty archive with Alt+F5 and hitting Delete allows deleting it!
This is because Viewer is invoked, actually. This is exactly the same as hitting
View on such a file. A clever, but unexpected, fallback :-) ]
3. Dirs exist. After Ctrl+Deleting in Branch mode, the .ZIP is not deleted and the
dirs are preserved.
However, in some cases the .ZIP is deleted, despite the presence of dirs! At
first I noticed that in some archives there were no files in the root, but
later tests showed that this is not the cause.
So, I can't determine reliably when an archive file (with dirs) will be deleted from
disk after all of its files have been deleted. What's the rule Kim?