[RFE] Additonal information on messages

[rougier]

Note, please see the IDEAS.org file in repository root for existing ideas; maybe
it's already there.

Is your feature request related to a problem? Please describe.
No related problem.

Describe the solution you'd like
For a custom interface ( nano-mu4e) using threads mode, I need to add information in the following way:

For every message, mark them with:

• message is first in message list (:is-first t)
• message is last in message list (:is-last t)
• message is the last in thread (:thread-is-last t)

For each thread root message, mark them with:

• thread root (:thread-is-root t)
• thread count (:thread-count #)
• thread unread count (:thread-unread-count #)
• thread unread first (:thread-unread-first docid)
• thread unread last (:thread-unread-last docid)

This information allows to control more finely how threads are displayed.

Describe alternatives you've considered
I'm currently using the found-handler hook to fill in the information myself using an instrument function

Additional context
See nano-mu4e

[djcb]

When requesting headers, there's :meta information in the blobs, e.g:

 :meta (:path 0a2:z :level 0 :date n69e5c20c :data-tstamp (0 0 0) :root t :thread-subject t))

which should allow for getting some of that information, though you'd need to do a bit of massaging.

Getting all of the information is some convenient way is bit bigger task. Let me think a bit about it.

[rougier]

Thanks. I'm actually populating the :meta field with the information above. Note this feature request is not an emergency at all (I can live with my temporary solution).