[Evolution] Evo 3.22.3: Inoperable horizontal scroll?

[Paul Smith <paul mad-scientist net>]

Hi all.  I'm using Ubuntu 16.10 with the latest Evo 3.22.3 from the
"Ubuntu Proposed".  However, this problem happened with Evo 3.22.1 as
well.

I have an issue where sometimes in the Preview pane when the content of
the message (html message) is too wide to fit in the pane I get a
horizontal scroll bar, but it doesn't work.  I can't click on it, I
can't drag it, etc.

The scroll bar shows up normally (that is it's small when it's not
"active" then when I mouse over it it gets bigger), but it's frozen at
the far left.

If I open the message in a new window (double-click) and make the window
small enough to get the scroll bar to appear, the same thing happens
(scroll bar is frozen).

I can use arrow keys to scroll sideways but not the scroll bar.

Note this doesn't happen for every HTML message which is too wide, but
it happens very often to me.  Most often on email from my code review
tool which contains a lot of tables used for formatting.

Anyone else seeing this?