Now that we no longer use tables for our message list, we can
more logically group messages together.
(imported from commit 9923a092f91a45fe3ef06f2f00e23e4e3fb62a37)
This experiment has been disabled for everyone for a while: if we
bring something like this back, it is not likely to be exactly the same,
and will be different enough to require a different implementation.
As it is, the summarization code was making a few code paths (rendering
especially) more complex, and is worth removing for simplicity's sake.
(imported from commit 6ac8cdc9f7077a5a1da01ab4268aba3db0bc43f8)
Previously, narrowing would only work from recipient rows, not
other message table rows (e.g. summary rows). This led to the trap
that you could add a narrows_by_recipient class to an element,
expect that narrowing would work, but the actual handler would
break or silently fail if it weren't part of a recipient row.
Now the click handler looks for the closest table row (tr). It's
encapsulated in rows.get_closest_row(), so if we go to a
non-table-based design, it should be easy to address in one
place.
(imported from commit e116b7573c4bb06599ced84a0adcf8dc23d63593)