This is the natural behavior that most users will
probably expect. If you need to go to All Messages when
topics are zoomed in, you can just hit ESC twice.
If you zoom into "more topics" for a stream that has
a LOT of topics, and then scroll down to the bottom,
and then zoom out by selecting "All messages" or
similar upper-left-sidebar options, we now try to scroll
the more recently active stream back into place after we scroll
out.
Before this change, it was possible for your lower left
sidebar to appear empty, as it would keep the
scroll offset from "more topics".
If our topic list isn't zoomed in, avoid calling
stream_list.zoom_out_topics().
This commit also introduces `zoomed_in` to track
our topic zooming state.
This small modules nicely breaks down the
responsibilities of topic_list and stream_list
when it comes to zooming in and out of topics
(also known as hitting "more topics" or "All
Streams).
Before this, neither module was clearly in
charge, and there were kind of complicated
callback mechanisms. The stream_list code
was asking topic_list to create click handlers
that called back into stream_list.
Now we just topic_zoom set up its own click
handlers and delegate out to the other two
modules.
Tim Abbott
Steve Howell