Enhancement Request: Copy book format(s) /save-to-disk to extra data folder

[ownedbycats]

Being able to copy a book file to the extra data folder from within Calibre may be helpful. Also slightly reduces the risk of a lock collision from leaving the folder open.

Use-case: A book released a new edition (or a fanfic with heavy revisions). The user wants to keep both copies, but not maintain separate book records.

The places I would expect to find this is either the context menu of a format, or the save-to-disk menu.

Thanks in advance.

[Kovid Goyal (kovid)]

This is too niche a use case for me to devote UI space for. It's really
not that hard to open the book folder and copya file into the data
sub-folder.