[MlMt] Preview again

[John D. Muccigrosso]

Once again the Preview pane has silently - and nearly invisibly - opened 
itself at the bottom of my inbox, making messages go “read” when I 
simply click on them. I have expanded and now shrunk it, but why does 
this keep happening? Maybe there should just be a preference to keep it 
closed (or better, not present) instead of having to close it to make it 
stop being active. I know Mail.app does it this way too, but I donʻt 
think itʻs smart there either.

John