[MlMt] 2.0 bug - opened messages not marked as read

[John D. Muccigrosso]

β 6043

I was getting messages being marked as read without opening them because 
the Viewer pref “Mark messages as read after X seconds” was checked 
with X=0. (I think that behavior is a bug too, because they should only 
be marked as read after viewing and I have the preview pane closed.) 
Anyway, now messages don’t seem to be getting marked as read at all, 
even after I open them.

John