[md-dev] api to get selected transaction

[Ryan Heaton]

I'd like to add an extension that adds custom marks (i.e. "tags") to
specific transactions.  But I'm not clear on how to get a handle for the
currently-selected or highlighted transaction.  The only kind of
"context" for the transaction I see is the right-click menu.  Can I add
an option to that?  Are there any other ways to do this?

-Ryan