A wxCommandEvent is passed to a message handler when a panel item command is issued (usually by a user action).
The command event types are as follows:
wxCommandEvent get-selection
wxCommandEvent is-selection
long ( get-selection)
Returns the identifier selection corresponding to the selected item, for example a listbox or menu item.
bool ( is-selection)
Returns 1 if the event was a selection event, 0 otherwise.