Hi,

I used a XamWebNumericEditor  and binding the Mask Property:

<ig:XamWebNumericEditor
            Value="{Binding Path=Valor, Mode=TwoWay, ValidatesOnExceptions=True}"
            Mask="{Binding Path=Mascara, Mode=OneWay}"
            Minimum="{Binding Path=MinNumerico, Mode=OneWay}"
            Maximum="{Binding Path=MaxNumerico, Mode=OneWay}"          
            HorizontalAlignment="Stretch" VerticalAlignment="Stretch"
            />

In Visual studio 2010 generte this Exception on Design view:

System.ArgumentException

Only this mask is allowed in XamWebNumericEditor: {double:-i.f} \n If you want to use the other masks consider using XamWebMaskedEditor instead.

at Infragistics.Silverlight.Controls.XamWebNumericEditor.b() at Infragistics.Silverlight.Controls.XamWebNumericEditor.InitializeManagers() at Infragistics.Silverlight.Controls.XamWebMaskedEditor.a(Object A_0, RoutedEventArgs A_1) at MS.Internal.CoreInvokeHandler.InvokeEventHandler(Int32 typeIndex, Delegate handlerDelegate, Object sender, Object args) at MS.Internal.JoltHelper.FireEvent(IntPtr unmanagedObj, IntPtr unmanagedObjArgs, Int32 argsTypeIndex, String eventName)