Main window should be focused after sending an email

I really love the After sending, enable undo for: X seconds feature but I found a small problem with it:

When I minimize or close the main Mailspring window, compose an email in the composer window, and send it, the composer window is closed and the main window which contains the undo button stays hidden, so I can’t click Undo unless I manually open the window. This removes the kind of confidence this feature gives to users and thus makes it pointless.

My suggestion is to .show() the window if closed and .focus() it otherwise.

(Originally posted by shroudedcode on GitHub.)

Hmm—this seems like a good idea. If you typically close / hide the main window while composing, you’re definitely a little out of luck. I’ll see if we can do this in an upcoming release. Would also accept a PR for this!

(Originally posted by bengotow on GitHub.)