[MlMt] Using tab & shift-tab to move focus among MM controls not working right (r5690)

[Eric Sharakan]

Hi Benny, here's one more odd behavior I've noticed in the more recent 
builds of MM.  I have the "use keyboard navigation to move focus between 
controls" option in the Shortcuts pane of the Keyboard system preference 
pane enabled.  I use this a lot in many Apps, including MM.

Recently, I've found it's no longer working correctly in MM.  It used to 
round-robin through the various panes and controls/focus points within 
those panes, but not anymore.  It's like the focus gets lost after I hit 
tab or shift-tab a few times, and then no matter how many times I 
continue to hit it, none of the controls become visibly enabled.

However, it does appear some focus is still set.  I noticed my keyboard 
shortcut to delete a message ('d') sometimes works even when it doesn't 
visibly appear the message metadata line has the focus.  Other times, 
the same key moves down to the next message in the list.  There is just 
no visible indication of which control has the focus.  It's rather 
unsettling for someone like me who relies heavily on tabbing through the 
various controls.

-Eric