Some of the work here was done Tomasz Kolek.
When we click on "more conversations" in "Private Messages,"
we call it being "zoomed in." Before this change, when
new PMs arrived, we would rebuild the list and zoom out
again. Now we track the zoomed_in state with a variable.
Also, if you are zoomed in and switch from one PM narrow
to another, we also keep you zoomed in.
This fix also removes some extraneous/redundant code.
Fixes: #2561
On hover, the transparency of muted stream/topic groups should turn up
to 0.6 so that they are easily readable by people looking to find a
particular stream/topic, but not completely opaque as to be confused
with a non-muted item.
Fixes: #2487.
The left sidebar will overflow its bounds (even when set to overflow:
hidden) and go behind other text on the sidebar above. By setting the
z-index to 0 we seem to solve the problem.
This is probably actually a webkit bug, but this makes it no longer
affect us.
Fixes#1899.
Steve Howell
Brock Whittaker
Tomasz Kolek
Tim Abbott
trueskawka