‘Mark as Not Junk’ fails if the mailbox is key

MailMate build 6083

If an email is being viewed (using anything other than the statistics view, of course), but it’s the mailbox that has keyboard focus, clicking on a ‘Mark as Not Junk’ has no effect.

Steps to reproduce:

1. Either find an email that’s been marked as junk, or mark one as junk.
   
2. Select the mailbox from the source list on the left.
   
3. Click on the open email’s ‘Mark as Not Junk’, nothing happens.

Selecting the email from the list allows the ‘Mark as Not Junk’ to work as expected.