This method notifies a control that the control is gaining focus.
HRESULT GotFocus( void );
NOERROR indicates success. If an error occurs, the appropriate HRESULT value is returned.
If a message sink exists, the control forwards this call to the IASClassMsgSink::GotFocus method.
IASControl::LostFocus, IASClassMsgSink::HandleGotFocus