Displaying read messages collapsed in Emacs

[Jani Nikula]

On Tue, 27 May 2014, kototama kototama <kototamo at gmail.com> wrote:
> Is it possible to display the thread with messages that have not the unread
> tag collapsed ?

Currently the only options (AFAIK) are expanding all messages, expanding
messages matching the query and collapsing the rest, or collapsing all
messages. If you do a search for tag:unread, and display a thread from
that search view, the messages not having unread tag will be collapsed.

I'd like to be able to expand/collapse based on user defined tags too,
independent of the query, in addition to the above mentioned.

BR,
Jani.