[MlMt] Header View

[David Schlangen]

With some recent update, the handy little triangle that toggled between 
compact and list view of the header of the current email disappeared, 
and the only way to change this now is via the menu. Which drives me 
mad. I can't be the only person who normally likes to save space 
(compact view), but often enough needs to know who exactly the 
recipients of an email were (list view)? Please bring back the little 
triangle!

- David.