[MlMt] Copying subject line keeps it selected, causing issues for replies

[Eric Sharakan]

Hi Benny and others, on r5933 (and a few of the earlier test releases), if I select the subject line of a message and use Cmd-C to copy it, the subject stays selected, even when switching away from the message and back.  This poses a problem when attempting to reply, as I have the "Only include selected text" option selected, as I get a message in the composer pane that includes just the still-selected subject line.

-Eric