Comment 2 for bug 16391

Bug #125023 is rather extensive. I looked it through and found discussions
about lots of things, but not about the particular problem I'm having (notably
that sizing of an _even_ number of buttons is wrong). Even if this bug is
related to 125023, it's much clearer and more obvious, easily reproducable and,
in my opinion, what the fix should change is obvious.

I can attach screenshots if you'd like. but I did not think that it was really
needed. It's so easy to reproduce (turn off window grouping to make the problem
more visible).