[gnome-games/wip/exalm/libhandy2: 6/7] preferences-window: Add back button

[Alexander Mikhaylenko <alexm src gnome org>]

commit d0f0951e9ea7563afb299a1934271d7f52ebdb86
Author: Alexander Mikhaylenko <exalm7659 gmail com>
Date:   Mon Sep 24 23:38:11 2018 +0500

    preferences-window: Add back button
    
    This will be used in the next commit to go back to sidebar in folded mode.

 data/ui/preferences-window.ui  | 24 ++++++++++++++++++++++++
 src/ui/preferences-window.vala |  4 ++++
 2 files changed, 28 insertions(+)
---
diff --git a/data/ui/preferences-window.ui b/data/ui/preferences-window.ui
index 491ebaf8..1d9e7035 100644
--- a/data/ui/preferences-window.ui
+++ b/data/ui/preferences-window.ui
@@ -41,6 +41,30 @@
                     <property name="visible">True</property>
                     <property name="hexpand">True</property>
                     <property name="show-close-button">True</property>
+                    <child>
+                      <object class="GtkButton" id="back_button">
+                        <property name="visible">False</property>
+                        <signal name="clicked" handler="on_back_clicked"/>
+                        <style>
+                          <class name="image-button"/>
+                        </style>
+                        <child internal-child="accessible">
+                          <object class="AtkObject" id="a11y-back">
+                            <property name="accessible-name" translatable="yes">Back</property>
+                          </object>
+                        </child>
+                        <child>
+                          <object class="GtkImage" id="back_image">
+                            <property name="visible">True</property>
+                            <property name="icon-name">go-previous-symbolic</property>
+                            <property name="icon-size">1</property>
+                          </object>
+                        </child>
+                      </object>
+                      <packing>
+                        <property name="pack-type">start</property>
+                      </packing>
+                    </child>
                   </object>
                 </child>
               </object>
diff --git a/src/ui/preferences-window.vala b/src/ui/preferences-window.vala
index a91a8b51..30dc2b66 100644
--- a/src/ui/preferences-window.vala
+++ b/src/ui/preferences-window.vala
@@ -84,4 +84,8 @@ private class Games.PreferencesWindow : Gtk.Window {
                titlebar_stack.remove (previous_subpage.header_bar);
                previous_subpage = null;
        }
+
+       [GtkCallback]
+       private void on_back_clicked () {
+       }
 }