[mu4e bug] Regressions with saving images

[jgoerzen]

Describe the bug

After upgrading from mu4e 1.4.15 to mu4e 1.8.14, I am encountering these issues:

1. There is no way to save all images like we used to have in the mu4e view.
2. While I can use the action menu to save attachments, I must use M-x image-save to save inline images.
3. M-x image-save does not preserve the filename. In fact, I can no longer even access the filenames of inline images.

There are some related issues:

• [mu4e rfe] allow users to download inline images/attachments #2173 suggested (setq gnus-inhibit-mime-unbuttonizing t) but that did not help me.
• mu4e-action-view-in-browser doesn't work with inline attachments... #758 discusses viewing in browser not working with inline attachments, but viewing in browser is something I highly wish to avoid due to the privacy implications. (And it's a number of years old and might have been resolved by View in browser with images #750 anyhow)

How to Reproduce

Receive a message with inline image attachments.

Observe they are not available for save in the action menu, and filenames are not preserved with M-x image-save. Also there is no way to save all attachments, regardless of type, anymore.

Environment
Debian bookworm with Doom emacs and mu4e 1.8.14.

Checklist

• you are running either an 1.8.x/1.10.x release or master (otherwise please upgrade)
• you can reproduce the problem without 3rd party extensions (including Doom/Evil, various extensions etc.)
• you have read all of the above

Please make sure you all items in the checklist are set/met before filing the ticket. Thank you!

[djcb]

Yeah, with the move to the gnus-based viewer we gained many features, and lost a few, which are slowly coming back...
I'm planning to update the mime-handling code for the next stable release (1.11.x --> 1.12)

[djcb]

A first version of this has landed in master, and it does bring back saving for disposition "inline" attachments and some other improvements; so closing this.

But note, unfortunately this is too big to be back-merged into the release branches for 1.10 (let alone 1.8).