As another piece of functionality, we are adding a sidebar, which demonstrates Gtk::MenuButton, Gtk::Revealer and Gtk::ListBox. The new widgets are added in the window.ui file.

The code to populate the sidebar with buttons for the words found in each file is a little too involved to go into here. But we'll look at the code to add the gears menu. As expected by now, the gears menu is specified in a Gtk::Builder ui file, gears_menu.ui

To connect the menu item to the new show-words setting, we use a Gio::Action corresponding to the given Gio::Settings key. In ExampleAppWindow's constructor:

// Connect the menu to the MenuButton m_gears, and bind the show-words setting
// to the win.show-words action and the "Words" menu item.
// (The connection between action and menu item is specified in gears_menu.ui.)
auto menu_builder = Gtk::Builder::create_from_resource("/org/gtkmm/exampleapp/gears_menu.ui");
auto object = menu_builder->get_object("menu");
auto menu = Glib::RefPtr<Gio::MenuModel>::cast_dynamic(object);
m_gears->set_menu_model(menu);
add_action(m_settings->create_action("show-words"));

What our application looks like now:

Source Code

File: exampleappwindow.h (For use with gtkmm 3, not gtkmm 2)

#ifndef GTKMM_EXAMPLEAPPWINDOW_H_
#define GTKMM_EXAMPLEAPPWINDOW_H_

#include <gtkmm.h>

class ExampleAppWindow : public Gtk::ApplicationWindow
{
public:
  ExampleAppWindow(BaseObjectType* cobject,
    const Glib::RefPtr<Gtk::Builder>& refBuilder);

  static ExampleAppWindow* create();

  void open_file_view(const Glib::RefPtr<Gio::File>& file);

protected:
  // Signal handlers
  void on_search_text_changed();
  void on_visible_child_changed();
  void on_find_word(const Gtk::Button* button);
  void on_reveal_child_changed();

  void update_words();

  Glib::RefPtr<Gtk::Builder> m_refBuilder;
  Glib::RefPtr<Gio::Settings> m_settings;
  Gtk::Stack* m_stack;
  Gtk::ToggleButton* m_search;
  Gtk::SearchBar* m_searchbar;
  Gtk::SearchEntry* m_searchentry;
  Gtk::MenuButton* m_gears;
  Gtk::Revealer* m_sidebar;
  Gtk::ListBox* m_words;
  Glib::RefPtr<Glib::Binding> m_prop_binding;
};

#endif /* GTKMM_EXAMPLEAPPWINDOW_H */

File: exampleappprefs.h (For use with gtkmm 3, not gtkmm 2)

#include "../step5/exampleappprefs.h"
// Equal to the corresponding file in step5

File: exampleapplication.h (For use with gtkmm 3, not gtkmm 2)

#include "../step4/exampleapplication.h"
// Equal to the corresponding file in step4

File: exampleapplication.cc (For use with gtkmm 3, not gtkmm 2)

#include "../step5/exampleapplication.cc"
// Equal to the corresponding file in step5

File: main.cc (For use with gtkmm 3, not gtkmm 2)

#include "../step5/main.cc"
// Equal to the corresponding file in step5

File: exampleappwindow.cc (For use with gtkmm 3, not gtkmm 2)

#include "exampleappwindow.h"
#include <iostream>
#include <stdexcept>
#include <set>

ExampleAppWindow::ExampleAppWindow(BaseObjectType* cobject,
  const Glib::RefPtr<Gtk::Builder>& refBuilder)
: Gtk::ApplicationWindow(cobject),
  m_refBuilder(refBuilder),
  m_settings(),
  m_stack(nullptr),
  m_search(nullptr),
  m_searchbar(nullptr),
  m_searchentry(nullptr),
  m_gears(nullptr),
  m_sidebar(nullptr),
  m_words(nullptr),
  m_prop_binding()
{
  // Get widgets from the Gtk::Builder file.
  m_refBuilder->get_widget("stack", m_stack);
  if (!m_stack)
    throw std::runtime_error("No \"stack\" object in window.ui");

  m_refBuilder->get_widget("search", m_search);
  if (!m_search)
    throw std::runtime_error("No \"search\" object in window.ui");

  m_refBuilder->get_widget("searchbar", m_searchbar);
  if (!m_searchbar)
    throw std::runtime_error("No \"searchbar\" object in window.ui");

  m_refBuilder->get_widget("searchentry", m_searchentry);
  if (!m_searchentry)
    throw std::runtime_error("No \"searchentry\" object in window.ui");

  m_refBuilder->get_widget("gears", m_gears);
  if (!m_gears)
    throw std::runtime_error("No \"gears\" object in window.ui");

  m_refBuilder->get_widget("sidebar", m_sidebar);
  if (!m_sidebar)
    throw std::runtime_error("No \"sidebar\" object in window.ui");

  m_refBuilder->get_widget("words", m_words);
  if (!m_words)
    throw std::runtime_error("No \"words\" object in window.ui");

  // Bind settings.
  m_settings = Gio::Settings::create("org.gtkmm.exampleapp");
  m_settings->bind("transition", m_stack->property_transition_type());
  m_settings->bind("show-words", m_sidebar->property_reveal_child());

  // Bind properties.
  m_prop_binding = Glib::Binding::bind_property(m_search->property_active(),
    m_searchbar->property_search_mode_enabled(), Glib::BINDING_BIDIRECTIONAL);

  // Connect signal handlers.
  m_searchentry->signal_search_changed().connect(
    sigc::mem_fun(*this, &ExampleAppWindow::on_search_text_changed));
  m_stack->property_visible_child().signal_changed().connect(
    sigc::mem_fun(*this, &ExampleAppWindow::on_visible_child_changed));
  m_sidebar->property_reveal_child().signal_changed().connect(
    sigc::mem_fun(*this, &ExampleAppWindow::on_reveal_child_changed));

  // Connect the menu to the MenuButton m_gears, and bind the show-words setting
  // to the win.show-words action and the "Words" menu item.
  // (The connection between action and menu item is specified in gears_menu.ui.)
  auto menu_builder = Gtk::Builder::create_from_resource("/org/gtkmm/exampleapp/gears_menu.ui");
  auto object = menu_builder->get_object("menu");
  auto menu = Glib::RefPtr<Gio::MenuModel>::cast_dynamic(object);
  if (!menu)
    throw std::runtime_error("No \"menu\" object in gears_menu.ui");

  m_gears->set_menu_model(menu);
  add_action(m_settings->create_action("show-words"));
}

//static
ExampleAppWindow* ExampleAppWindow::create()
{
  // Load the Builder file and instantiate its widgets.
  auto refBuilder = Gtk::Builder::create_from_resource("/org/gtkmm/exampleapp/window.ui");

  ExampleAppWindow* window = nullptr;
  refBuilder->get_widget_derived("app_window", window);
  if (!window)
    throw std::runtime_error("No \"app_window\" object in window.ui");

  return window;
}

void ExampleAppWindow::open_file_view(const Glib::RefPtr<Gio::File>& file)
{
  const auto basename = file->get_basename();

  auto scrolled = Gtk::make_managed<Gtk::ScrolledWindow>();
  scrolled->set_hexpand(true);
  scrolled->set_vexpand(true);
  scrolled->show();
  auto view = Gtk::make_managed<Gtk::TextView>();
  view->set_editable(false);
  view->set_cursor_visible(false);
  view->show();
  scrolled->add(*view);
  m_stack->add(*scrolled, basename, basename);

  auto buffer = view->get_buffer();
  try
  {
    char* contents = nullptr;
    gsize length = 0;
    
    file->load_contents(contents, length);
    buffer->set_text(contents, contents+length);
    g_free(contents);
  }
  catch (const Glib::Error& ex)
  {
    std::cout << "ExampleAppWindow::open_file_view(\"" << file->get_parse_name()
      << "\"):\n  " << ex.what() << std::endl;
    return;
  }

  auto tag = buffer->create_tag();
  m_settings->bind("font", tag->property_font());
  buffer->apply_tag(tag, buffer->begin(), buffer->end());

  m_search->set_sensitive(true);
  update_words();
}

void ExampleAppWindow::on_search_text_changed()
{
  const auto text = m_searchentry->get_text();
  if (text.empty())
    return;

  auto tab = dynamic_cast<Gtk::ScrolledWindow*>(m_stack->get_visible_child());
  if (!tab)
  {
    std::cout << "ExampleAppWindow::on_search_text_changed(): No visible child." << std::endl;
    return;
  }

  auto view = dynamic_cast<Gtk::TextView*>(tab->get_child());
  if (!view)
  {
    std::cout << "ExampleAppWindow::on_search_text_changed(): No visible text view." << std::endl;
    return;
  }

  // Very simple-minded search implementation.
  auto buffer = view->get_buffer();
  Gtk::TextIter match_start;
  Gtk::TextIter match_end;
  if (buffer->begin().forward_search(text, Gtk::TEXT_SEARCH_CASE_INSENSITIVE,
      match_start, match_end))
  {
    buffer->select_range(match_start, match_end);
    view->scroll_to(match_start);
  }
}

void ExampleAppWindow::on_visible_child_changed()
{
  m_searchbar->set_search_mode(false);
  update_words();
}

void ExampleAppWindow::on_find_word(const Gtk::Button* button)
{
  m_searchentry->set_text(button->get_label());
}

void ExampleAppWindow::on_reveal_child_changed()
{
  update_words();
}

void ExampleAppWindow::update_words()
{
  auto tab = dynamic_cast<Gtk::ScrolledWindow*>(m_stack->get_visible_child());
  if (!tab)
    return;

  auto view = dynamic_cast<Gtk::TextView*>(tab->get_child());
  if (!view)
  {
    std::cout << "ExampleAppWindow::update_words(): No visible text view." << std::endl;
    return;
  }
  auto buffer = view->get_buffer();

  // Find all words in the text buffer.
  std::set<Glib::ustring> words;
  auto start = buffer->begin();
  Gtk::TextIter end;
  while (start)
  {
    while (start && !start.starts_word())
      ++start;

    if (!start)
      break;

    end = start;
    end.forward_word_end();
    if (start == end)
      break;

    auto word = buffer->get_text(start, end, false);
    words.insert(word.lowercase());
    start = end;
  }

  // Remove old children from the ListBox.
  auto old_children = m_words->get_children();
  for (auto child : old_children)
  {
    m_words->remove(*child);
    delete child;
  }

  // Add new child buttons, one per unique word.
  for (const auto& word : words)
  {
    auto row = Gtk::make_managed<Gtk::Button>(word);
    row->signal_clicked().connect(sigc::bind(sigc::mem_fun(*this,
      &ExampleAppWindow::on_find_word), row));
    row->show();
    m_words->add(*row);
  }
}

File: exampleappprefs.cc (For use with gtkmm 3, not gtkmm 2)

#include "../step5/exampleappprefs.cc"
// Equal to the corresponding file in step5

File: exampleapp.gresource.xml (For use with gtkmm 3, not gtkmm 2)

<?xml version="1.0" encoding="UTF-8"?>
<gresources>
  <gresource prefix="/org/gtkmm/exampleapp">
    <file preprocess="xml-stripblanks">window.ui</file>
    <file preprocess="xml-stripblanks">app_menu.ui</file>
    <file preprocess="xml-stripblanks">gears_menu.ui</file>
    <file preprocess="xml-stripblanks">prefs.ui</file>
  </gresource>
</gresources>

File: gears_menu.ui (For use with gtkmm 3, not gtkmm 2)

<?xml version="1.0"?>
<interface>
  <!-- interface-requires gtk+ 3.0 -->
  <menu id="menu">
    <section>
      <item>
        <attribute name="label" translatable="yes">_Words</attribute>
        <attribute name="action">win.show-words</attribute>
      </item>
    </section>
  </menu>
</interface>

File: window.ui (For use with gtkmm 3, not gtkmm 2)

<?xml version="1.0" encoding="UTF-8"?>
<interface>
  <!-- interface-requires gtk+ 3.8 -->
  <object class="GtkApplicationWindow" id="app_window">
    <property name="title" translatable="yes">Example Application</property>
    <property name="default-width">600</property>
    <property name="default-height">400</property>
    <child>
      <object class="GtkBox" id="content_box">
        <property name="visible">True</property>
        <property name="orientation">vertical</property>
        <child>
          <object class="GtkHeaderBar" id="header">
            <property name="visible">True</property>
            <child type="title">
              <object class="GtkStackSwitcher" id="tabs">
                <property name="visible">True</property>
                <property name="stack">stack</property>
              </object>
            </child>
            <child>
              <object class="GtkToggleButton" id="search">
                <property name="visible">True</property>
                <property name="sensitive">False</property>
                <style>
                  <class name="image-button"/>
                </style>
                <child>
                  <object class="GtkImage" id="search-icon">
                    <property name="visible">True</property>
                    <property name="icon-name">edit-find-symbolic</property>
                    <property name="icon-size">1</property>
                  </object>
                </child>
              </object>
              <packing>
                <property name="pack-type">end</property>
              </packing>
            </child>
            <child>
              <object class="GtkMenuButton" id="gears">
                <property name="visible">True</property>
                <property name="direction">none</property>
                <property name="use-popover">True</property>
                <style>
                  <class name="image-button"/>
                </style>
              </object>
              <packing>
                <property name="pack-type">end</property>
              </packing>
            </child>
          </object>
        </child>
        <child>
          <object class="GtkSearchBar" id="searchbar">
            <property name="visible">True</property>
            <child>
              <object class="GtkSearchEntry" id="searchentry">
                <property name="visible">True</property>
              </object>
            </child>
          </object>
        </child>
        <child>
          <object class="GtkBox" id="hbox">
            <property name="visible">True</property>
            <child>
              <object class="GtkRevealer" id="sidebar">
                <property name="visible">True</property>
                <property name="transition-type">slide-right</property>
                <child>
                 <object class="GtkScrolledWindow" id="sidebar-sw">
                   <property name="visible">True</property>
                   <property name="hscrollbar-policy">never</property>
                   <property name="vscrollbar-policy">automatic</property>
                   <child>
                     <object class="GtkListBox" id="words">
                       <property name="visible">True</property>
                       <property name="selection-mode">none</property>
                     </object>
                   </child>
                 </object>
                </child>
              </object>
            </child>
            <child>
              <object class="GtkStack" id="stack">
                <property name="visible">True</property>
                <property name="transition-duration">500</property>
              </object>
            </child>
          </object>
        </child>
      </object>
    </child>
  </object>
</interface>

File: org.gtkmm.exampleapp.gschema.xml (For use with gtkmm 3, not gtkmm 2)

<?xml version="1.0" encoding="UTF-8"?>
<schemalist>
  <schema path="/org/gtkmm/exampleapp/" id="org.gtkmm.exampleapp">
    <key name="font" type="s">
      <default>'Monospace 12'</default>
      <summary>Font</summary>
      <description>The font to be used for content.</description>
    </key>
    <key name="transition" type="s">
      <choices>
        <choice value='none'/>
        <choice value='crossfade'/>
        <choice value='slide-left-right'/>
      </choices>
      <default>'none'</default>
      <summary>Transition</summary>
      <description>The transition to use when switching tabs.</description>
    </key>
    <key name="show-words" type="b">
      <default>false</default>
      <summary>Show words</summary>
      <description>Whether to show a word list in the sidebar.</description>
    </key>
  </schema>
</schemalist>