[gnome-tetravex] Give focus to new-game button.

[Arnaud B. <arnaudb src gnome org>]

commit 2a1636f68fc77a34a80349f89da9fa6fd407534d
Author: Arnaud Bonatti <arnaud bonatti gmail com>
Date:   Wed Oct 16 03:34:49 2019 +0200

    Give focus to new-game button.

 src/gnome-tetravex.vala | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
---
diff --git a/src/gnome-tetravex.vala b/src/gnome-tetravex.vala
index f70f0f7..5c234df 100644
--- a/src/gnome-tetravex.vala
+++ b/src/gnome-tetravex.vala
@@ -42,6 +42,7 @@ private class Tetravex : Gtk.Application
 
     private PuzzleView view;
     private Button pause_button;
+    private Button new_game_button;
 
     private ApplicationWindow window;
     private int window_width;
@@ -319,7 +320,7 @@ private class Tetravex : Gtk.Application
         play_pause_stack.add_named (pause_button, "pause");
         grid.attach (play_pause_stack, 0, 1, 1, 1);
 
-        Button new_game_button  = new BottomButton ("view-refresh-symbolic",
+        new_game_button         = new BottomButton ("view-refresh-symbolic",
                                                     "app.new-game",
         /* Translators: tooltip text of the "restart"/new game button, in the bottom bar */
                                                     _("Start a new game"),
@@ -589,6 +590,7 @@ private class Tetravex : Gtk.Application
         view.hide_right_sockets ();
 
         score_overlay.show ();
+        new_game_button.grab_focus ();
     }
 
     private void new_game_cb ()