root/data/resources/ui/window.ui

<?xml version="1.0" encoding="UTF-8"?>
<interface>
  <menu id="primary_menu">
    <section>
      <!-- <item> -->
      <!--   <attribute name="label" translatable="yes">_Preferences</attribute> -->
      <!--   <attribute name="action">app.preferences</attribute> -->
      <!-- </item> -->
      <item>
        <attribute name="label" translatable="yes">_Keyboard Shortcuts</attribute>
        <attribute name="action">app.shortcuts</attribute>
      </item>
      <item>
        <attribute name="label" translatable="yes">_About Sunrise</attribute>
        <attribute name="action">app.about</attribute>
      </item>
    </section>
  </menu>
  <template class="ExampleApplicationWindow" parent="AdwApplicationWindow">
    <child>
      <object class="GtkBox">
        <property name="orientation">vertical</property>

        <child>
          <object class="AdwHeaderBar" id="headerbar">
            <child type="end">
              <object class="GtkMenuButton" id="appmenu_button">
                <property name="icon-name">open-menu-symbolic</property>
                <property name="menu-model">primary_menu</property>
                <property name="primary">True</property>
                <property name="tooltip-text" translatable="yes">Main Menu</property>
              </object>
            </child>
          </object>
        </child>

        <child>
          <object class="AdwPreferencesPage">
            <child>
              <object class="AdwPreferencesGroup">
                <property name="title" translatable="yes">Sun Times</property>

                <child type="header-suffix">
                  <object class="GtkDropDown" id="location">
                    <property name="enable-search">True</property>
                    <property name="search-match-mode">prefix</property>
                    <property name="expression">
                      <lookup type="GtkStringObject" name="string"></lookup>
                    </property>

                  </object>
                </child>

                <child>
                  <object class="AdwSpinRow" id="date">
                    <property name="title" translatable="yes">Date</property>
                    <property name="wrap">True</property>
                    <property name="adjustment">
                      <object class="GtkAdjustment">
                        <property name="lower">-365</property>
                        <property name="upper">365</property>
                        <property name="value">0</property>
                        <property name="page-increment">1</property>
                        <property name="step-increment">1</property>
                      </object>
                    </property>
                  </object>
                </child>

                <child>
                  <object class="AdwActionRow">
                    <property name="title" translatable="yes">Sunrise</property>
                    <child>
                      <object class="GtkLabel" id="sunrise">
                        <attributes>
                          <attribute name="weight" value="PANGO_WEIGHT_BOLD"/>
                        </attributes>
                      </object>
                    </child>
                    <child>
                      <object class="GtkImage">
                        <property name="icon-name">daytime-sunrise-symbolic</property>
                        <style>
                          <class name="sunrise-icon"/>
                        </style>
                      </object>
                    </child>

                  </object>
                </child>

                <child>
                  <object class="AdwActionRow">
                    <property name="title" translatable="yes">Sundown</property>
                    <child>
                      <object class="GtkLabel" id="sundown">
                        <attributes>
                          <attribute name="weight" value="PANGO_WEIGHT_BOLD"/>
                        </attributes>
                      </object>
                    </child>
                    <child>
                      <object class="GtkImage">
                        <property name="icon-name">daytime-sunset-symbolic</property>
                        <style>
                          <class name="sunset-icon"/>
                        </style>
                      </object>
                    </child>
                  </object>
                </child>

                <style>
                  <class name="asdf"/>
                </style>
              </object>
            </child>
          </object>
        </child>

      </object>
    </child>
  </template>
</interface>