WPF

<ResourceDictionary>
    <ResourceDictionary.MergedDictionaries>
        <ResourceDictionary Source="/Assembly;component/NewSkin.xaml" />
    </ResourceDictionary.MergedDictionaries>
</ResourceDictionary>

<!--Global View Model Locator-->
<vm:ViewModelLocator x:Key="Locator"
                     d:IsDataSource="True" />

class FrameworkElement : UIElement
    {
        public static readonly DependencyProperty NumberProperty;

        public FrameworkElement() { }

        static FrameworkElement()
        {
            FrameworkPropertyMetadata metadata =
                new FrameworkPropertyMetadata(Double.NaN,
                                              FrameworkPropertyMetadataOptions.AffectsMeasure);

            NumberProperty = DependencyProperty.Register("Number",//Propertie name
                                                          typeof(Double),//Data used by the prpertie
                                                          typeof(FrameworkElement),//The type that owns the propertie
                                                          metadata,//Meta data object
                                                          new ValidateValueCallback(FrameworkElement.IsNumberValid));//Validation callback

        }

        public Double Number
        {
            set { SetValue(NumberProperty, value); }
            get { return (Double)GetValue(NumberProperty); }
        }


        private static Boolean IsNumberValid(object value)
        {
            Double number = (Double)value;

            if ((number < 0) || (number > 100))
                return false;
            return true;
        }
    }