Dear Maintainer,

When I summon the shutdown/restart/logout modal via super-key overview, neither
button on the modal has focus. Previously, the "Cancel" button had focus. I
would like one of the buttons to have focus so that I can use the keyboard to
TAB between the buttons and hit RETURN to select one.

These are the steps to reproduce this:
 * Hit the SUPER key to bring up the overview
 * Start searching for "shutdown"
 * When an option called "Power Off" appears, hit RETURN to select it
 * A "Power off" modal then appears. The "Cancel" button has focus very briefly
but losses it almost immediately.

The same problem occurs with the Logout and Restart modals.

As well as neither button having focus, I can't hit the ESC key to dismiss the
modal.

Interestingly, if I use the mouse to open the main GNOME Shell menu (clicking
in the top-right), open the Power off sub-menu and then select "Power off",
"Restart" or "Logout" form there, the modal then behaves as expected. So this
problem seems to be specific to selecting the Power Off/Restart/Logout modals
via the overview search.

I've confirmed that I get the same behaviour with user extensions disabled.