+ @event{EVT_COMBOBOX_DROPDOWN(id, func)}
+ Process a wxEVT_COMMAND_COMBOBOX_DROPDOWN event, which is generated
+ when the popup window is shown (drops down).
+ @event{EVT_COMBOBOX_CLOSEUP(id, func)}
+ Process a wxEVT_COMMAND_COMBOBOX_CLOSEUP event, which is generated
+ when the popup window of the combo control disappears (closes up).
+ You should avoid adding or deleting items in this event.