+extern "C" {
+static void
+gtkcombo_text_changed_callback( GtkWidget *WXUNUSED(widget), wxComboBox *combo )
+{
+    if (g_isIdle) wxapp_install_idle_handler();
+
+    if (combo->m_ignoreNextUpdate)
+    {
+        combo->m_ignoreNextUpdate = false;
+        return;
+    }
+
+    if (!combo->m_hasVMT) return;
+
+    wxCommandEvent event( wxEVT_COMMAND_TEXT_UPDATED, combo->GetId() );
+    event.SetString( combo->GetValue() );
+    event.SetEventObject( combo );
+    combo->GetEventHandler()->ProcessEvent( event );
+}
+}
+
+extern "C" {
+static void
+gtkcombo_dummy_callback(GtkEntry *WXUNUSED(entry), GtkCombo *WXUNUSED(combo))
+{
+}
+}
+
+extern "C" {
+static void
+gtkcombo_popup_hide_callback(GtkCombo *WXUNUSED(gtk_combo), wxComboBox *combo)
+{
+    // when the popup is hidden, throw a SELECTED event only if the combobox
+    // selection changed.
+    const int curSelection = combo->GetCurrentSelection();
+
+    const bool hasChanged = curSelection != g_SelectionBeforePopup;
+
+    // reset the selection flag to value meaning that it is hidden and do it
+    // now, before generating the events, so that GetSelection() returns the
+    // new value from the event handler
+    g_SelectionBeforePopup = wxID_NONE;
+
+    if ( hasChanged )
+    {
+        wxCommandEvent event( wxEVT_COMMAND_COMBOBOX_SELECTED, combo->GetId() );
+        event.SetInt( curSelection );
+        event.SetString( combo->GetStringSelection() );
+        event.SetEventObject( combo );
+        combo->GetEventHandler()->ProcessEvent( event );
+
+        // for consistency with the other ports, send TEXT event
+        wxCommandEvent event2( wxEVT_COMMAND_TEXT_UPDATED, combo->GetId() );
+        event2.SetString( combo->GetStringSelection() );
+        event2.SetEventObject( combo );
+        combo->GetEventHandler()->ProcessEvent( event2 );
+    }
+}
+}
+
+extern "C" {
+static void
+gtkcombo_popup_show_callback(GtkCombo *WXUNUSED(gtk_combo), wxComboBox *combo)
+{
+    // store the combobox selection value before the popup is shown
+    g_SelectionBeforePopup = combo->GetCurrentSelection();
+}
+}