[gnome-nibbles] Fix display of level completed label and next level button

[Michael Catanzaro <mcatanzaro src gnome org>]

commit ea9a183b2a0f3e9b2339c6f21b802b377c5bdefb
Author: Pedro Aldatxarren <pedro areizaga gmail com>
Date:   Tue Jun 13 00:46:35 2017 +0200

    Fix display of level completed label and next level button
    
    Fixes #22

 src/gnome-nibbles.vala | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/src/gnome-nibbles.vala b/src/gnome-nibbles.vala
index 1e78d64..4b7260c 100644
--- a/src/gnome-nibbles.vala
+++ b/src/gnome-nibbles.vala
@@ -876,6 +876,8 @@ public class Nibbles : Gtk.Application
         if (game.current_level == NibblesGame.MAX_LEVEL)
             return;
 
+        view.hide ();
+
         new_game_action.set_enabled (false);
         pause_action.set_enabled (false);
 
@@ -900,6 +902,8 @@ public class Nibbles : Gtk.Application
 
             headerbar.set_title (_("Level %d").printf (game.current_level));
 
+            view.show ();
+
             restart_game ();
         });