[gtkmm] C++11: tests/examples: Use override keyword.

[Murray Cumming <murrayc src gnome org>]

commit d8e1d0c7c7ea753201406edda66354606e12c073
Author: Murray Cumming <murrayc murrayc com>
Date:   Tue Oct 27 09:43:21 2015 +0100

    C++11: tests/examples: Use override keyword.

 demos/gtk-demo/example_change_display.cc     |    2 +-
 demos/gtk-demo/example_iconbrowser.cc        |    4 ++--
 demos/gtk-demo/example_sizegroup.cc          |    2 +-
 demos/gtk-demo/example_treeview_treestore.cc |    2 +-
 tests/main_with_options/main.cc              |    6 +++---
 5 files changed, 8 insertions(+), 8 deletions(-)
---
diff --git a/demos/gtk-demo/example_change_display.cc b/demos/gtk-demo/example_change_display.cc
index 67a33f6..0cd506b 100644
--- a/demos/gtk-demo/example_change_display.cc
+++ b/demos/gtk-demo/example_change_display.cc
@@ -64,7 +64,7 @@ protected:
 
   virtual bool on_popup_button_release_event(GdkEventButton* event);
 
-  virtual void on_response(int response_id);
+  void on_response(int response_id) override;
 
 
   class ModelColumns_Display : public Gtk::TreeModelColumnRecord
diff --git a/demos/gtk-demo/example_iconbrowser.cc b/demos/gtk-demo/example_iconbrowser.cc
index 477d0b3..cccadc2 100644
--- a/demos/gtk-demo/example_iconbrowser.cc
+++ b/demos/gtk-demo/example_iconbrowser.cc
@@ -73,8 +73,8 @@ protected:
   IconInfoStore();
 
   // Overridden virtual function:
-  virtual bool drag_data_get_vfunc(const Gtk::TreeModel::Path& path,
-    Gtk::SelectionData& selection_data) const;
+  bool drag_data_get_vfunc(const Gtk::TreeModel::Path& path,
+    Gtk::SelectionData& selection_data) const override;
 
 private:
   Gtk::TreeModelColumn<Glib::ustring> m_text_column;
diff --git a/demos/gtk-demo/example_sizegroup.cc b/demos/gtk-demo/example_sizegroup.cc
index be77930..95d246e 100644
--- a/demos/gtk-demo/example_sizegroup.cc
+++ b/demos/gtk-demo/example_sizegroup.cc
@@ -30,7 +30,7 @@ protected:
   virtual void add_row(Gtk::Grid& grid, int row, const Glib::RefPtr<Gtk::SizeGroup>& size_group, const 
Glib::ustring& label_text, const std::list<Glib::ustring>& options);
   virtual Gtk::ComboBoxText* create_combobox(const std::list<Glib::ustring>& strings);
 
-  virtual void on_response(int response_id);
+  void on_response(int response_id) override;
 
   //Member widgets:
   Gtk::Frame m_Frame_Color, m_Frame_Line;
diff --git a/demos/gtk-demo/example_treeview_treestore.cc b/demos/gtk-demo/example_treeview_treestore.cc
index bd2c62e..6d121b6 100644
--- a/demos/gtk-demo/example_treeview_treestore.cc
+++ b/demos/gtk-demo/example_treeview_treestore.cc
@@ -38,7 +38,7 @@ public:
 
 protected:
   //vfunc overrides:
-  virtual void on_realize();
+  void on_realize() override;
 
   virtual void create_model();
   virtual void add_columns();
diff --git a/tests/main_with_options/main.cc b/tests/main_with_options/main.cc
index e5ee18a..66e3f11 100644
--- a/tests/main_with_options/main.cc
+++ b/tests/main_with_options/main.cc
@@ -26,9 +26,9 @@ class ExampleOptionGroup : public Glib::OptionGroup
 public:
   ExampleOptionGroup();
 
-  virtual bool on_pre_parse(Glib::OptionContext& context, Glib::OptionGroup& group);
-  virtual bool on_post_parse(Glib::OptionContext& context, Glib::OptionGroup& group);
-  virtual void on_error(Glib::OptionContext& context, Glib::OptionGroup& group);
+  bool on_pre_parse(Glib::OptionContext& context, Glib::OptionGroup& group) override;
+  bool on_post_parse(Glib::OptionContext& context, Glib::OptionGroup& group) override;
+  void on_error(Glib::OptionContext& context, Glib::OptionGroup& group) override;
   
   //These int instances should live as long as the OptionGroup to which they are added, 
   //and as long as the OptionContext to which those OptionGroups are added.