[gnome-nibbles] Set default widgets for the pre-game screens.

[Iulian Radu <iulianradu src gnome org>]

commit b9d2cf58d396a6de4b106e3cac94bc54d56fff7a
Author: Iulian Radu <iulian radu67 gmail com>
Date:   Mon Aug 15 13:38:31 2016 +0300

    Set default widgets for the pre-game screens.
    
    This allows the user to just press enter until the game starts after
    opening Nibbles.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=769838

 data/nibbles.ui        |    6 ++++--
 src/gnome-nibbles.vala |   14 +++++++++++---
 2 files changed, 15 insertions(+), 5 deletions(-)
---
diff --git a/data/nibbles.ui b/data/nibbles.ui
index ad2a050..646e326 100644
--- a/data/nibbles.ui
+++ b/data/nibbles.ui
@@ -326,8 +326,9 @@
                                             </packing>
                                         </child>
                                         <child>
-                                            <object class="GtkButton">
+                                            <object class="GtkButton" id="next_button">
                                                 <property name="visible">True</property>
+                                                <property name="can-default">True</property>
                                                 <property name="use-underline">True</property>
                                                 <property name="label" translatable="yes">_Next</property>
                                                 <property 
name="action-name">app.show-controls-screen</property>
@@ -377,8 +378,9 @@
                                             </object>
                                         </child>
                                         <child>
-                                            <object class="GtkButton">
+                                            <object class="GtkButton" id="start_button">
                                                 <property name="visible">True</property>
+                                                <property name="can-default">True</property>
                                                 <property name="use-underline">True</property>
                                                 <property name="label" translatable="yes">_Start</property>
                                                 <property name="action-name">app.start-game</property>
diff --git a/src/gnome-nibbles.vala b/src/gnome-nibbles.vala
index c57a027..84bc636 100644
--- a/src/gnome-nibbles.vala
+++ b/src/gnome-nibbles.vala
@@ -40,6 +40,8 @@ public class Nibbles : Gtk.Application
     /* Pre-game screen widgets */
     private Gee.LinkedList<Gtk.ToggleButton> number_of_players_buttons;
     private Gee.LinkedList<Gtk.ToggleButton> number_of_ai_buttons;
+    private Gtk.Button next_button;
+    private Gtk.Button start_button;
 
     private Gtk.Box grids_box;
     private Gdk.Pixbuf arrow_pixbuf;
@@ -194,6 +196,8 @@ public class Nibbles : Gtk.Application
             button.toggled.connect (change_number_of_ai_cb);
             number_of_ai_buttons.add (button);
         }
+        next_button = (Gtk.Button) builder.get_object ("next_button");
+        start_button = (Gtk.Button) builder.get_object ("start_button");
         grids_box = (Gtk.Box) builder.get_object ("grids_box");
         window.set_titlebar (headerbar);
 
@@ -544,12 +548,14 @@ public class Nibbles : Gtk.Application
         new_game_button.hide ();
         pause_button.hide ();
 
+        number_of_players_buttons[game.numhumans - 1].set_active (true);
+        number_of_ai_buttons[game.numai].set_active (true);
+
+        window.set_default (next_button);
+
         main_stack.set_transition_type (Gtk.StackTransitionType.NONE);
         main_stack.set_visible_child_name ("number_of_players");
         main_stack.set_transition_type (Gtk.StackTransitionType.SLIDE_UP);
-
-        number_of_players_buttons[game.numhumans - 1].set_active (true);
-        number_of_ai_buttons[game.numai].set_active (true);
     }
 
     private void show_controls_screen_cb ()
@@ -600,6 +606,8 @@ public class Nibbles : Gtk.Application
             }
         }
 
+        window.set_default (start_button);
+
         main_stack.set_visible_child_name ("controls");
     }