Only one control can have the focus at a time. Focus changes in response to such events as a user pressing a key or speaking a command. The form is responsible for managing which control has focus. To receive the focus, a control must meet the following criteria:
When a control receives the input focus, its form invokes IASControl::GotFocus. When a control loses focus, the form invokes IASControl::LostFocus.
A control can determine which control currently has focus by invoking its form’s IASForm::GetFocus method. It can request the focus by invoking its form’s IASForm::SetFocus method.