Add a TODO comment for wxVListBox refactoring

Just note that it would be better to avoid duplicating the code already
existing in another place in wxVListBoxComboPopup::SendComboBoxEvent().

src/generic/odcombo.cpp

@@ -233,6 +233,11 @@ void wxVListBoxComboPopup::DismissWithEvent()
 
 void wxVListBoxComboPopup::SendComboBoxEvent( int selection )
 {
+    // TODO: wxVListBox should be refactored to inherit from wxItemContainer
+    //       and then we would be able to just call SendSelectionChangedEvent()
+    //       (which, itself, should be moved down to wxItemContainer from
+    //       wxControlWithItemsBase) instead of duplicating its code.
+
     wxCommandEvent evt(wxEVT_COMBOBOX,m_combo->GetId());
 
     evt.SetEventObject(m_combo);