Comment 1 for bug 1616203

Fixed for the next release. Buttons can now be focused and the page can be scrolled via the PageUp / PageDown keys (by pressing Tab first). ESC is also a shortcut to quickly get back to the main menu too.

Commits that address this:
* https://bitbucket.org/ubuntu-mate/ubuntu-mate-welcome/commits/4b0305f9d6e6f0e551cf24401992d78c6e5cd1db
* https://bitbucket.org/ubuntu-mate/ubuntu-mate-welcome/commits/f18e7aafa569efdd56c2dac206eb29876a84ee1c