<telerik:RadNumericTextBox ID="RadNumericTextBox1" runat="server"
MinValue="-999" MaxValue="999" NumberFormat-DecimalSeparator=","
Type="Number" AllowOutOfRangeAutoCorrect="false" DataType="System.Decimal" NumberFormat-DecimalDigits="4"></telerik:RadNumericTextBox>
1) type in "12345,4321"
2) blur and the control give an error. The typed value became: "12345.4321"
3) The comma "," decimal separator is changed into dot "."