gnome-control-center/panels/keyboard/cc-input-list-box.ui

<?xml version="1.0" encoding="UTF-8"?>
<interface>
  <!-- interface-requires gtk+ 3.0 -->
  <template class="CcInputListBox" parent="AdwBin">

    <child>
      <object class="GtkListBox" id="listbox">
        <property name="hexpand">True</property>
        <property name="vexpand">True</property>
        <property name="selection-mode">none</property>
        <signal name="row_activated" handler="input_row_activated_cb" object="CcInputListBox" swapped="yes"/>
        <signal name="keynav_failed" handler="keynav_failed_cb" object="CcInputListBox" swapped="yes"/>
        <style>
          <class name="boxed-list"/>
        </style>
        <child>
          <object class="GtkListBoxRow" id="no_inputs_row">
            <property name="selectable">False</property>
            <property name="activatable">False</property>
            <child>
              <object class="GtkLabel">
                <property name="margin_bottom">8</property>
                <property name="margin_top">8</property>
                <property name="label" translatable="yes">No input source selected</property>
              </object>
            </child>
          </object>
        </child>
        <child>
          <object class="GtkListBoxRow" id="add_input_row">
            <property name="selectable">False</property>
            <child>
              <object class="GtkImage">
                <property name="hexpand">True</property>
                <property name="height_request">50</property>
                <property name="margin_start">12</property>
                <property name="margin_end">12</property>
                <property name="icon-name">list-add-symbolic</property>
              </object>
            </child>
          </object>
        </child>
      </object>
    </child>

  </template>
</interface>