ННовичокКонечно же можно воспользоваться и KeyPress() и InteractiveChange() и Valid и LostFocus, всё это можно сделать....но для чего в TextBox стоит метод RangeLow(контроль нижней границы, как я понимаю ), как им пользоваться, и в чём отличие от приведённых выше методов
Ну, прочитайте же, наконец Хелп!!!
Visual FoxPro 9.0

RangeLow Event

For a spinner or text box, occurs when the control loses the focus. For a combo box or list box, occurs when the control receives the focus.


PROCEDURE Object.RangeLow


Remarks
Applies To: ComboBox | ListBox | Spinner | TextBox

A RangeLow event can return a numeric value to Visual FoxPro through a RETURN statement. For a spinner or a text box with a numeric value, if the value returned to Visual FoxPro is greater than the value entered in the control, the control retains the focus. For a combo box or list box, the value returned to Visual FoxPro specifies which item in the control is initially selected, For example, if 2 is returned to Visual FoxPro, the second item in the control is initially selected.

See Also
Reference
KeyboardHighValue, KeyboardLowValue Properties
RangeHigh Event
RETURN Command
SpinnerHighValue, SpinnerLowValue Properties

Other Resources
Events (Visual FoxPro)