SL DependencyProperty:

#region IsVisible (DependencyProperty)

        public bool IsVisible
        {
            get
            {
                return (bool)GetValue(IsVisibleProperty);
            }
            set
            { SetValue(IsVisibleProperty, value); }
        }
        public static readonly DependencyProperty IsVisibleProperty =
            DependencyProperty.Register("IsVisible", typeof(bool), typeof(MainPage),
              new PropertyMetadata(true));

        #endregion IsVisible (DependencyProperty)

SL VisibilityConverter:

    public class VisibilityConverter : IValueConverter
    {
        public object Convert(
            object value,
            Type targetType,
            object parameter,
            CultureInfo culture)
        {
            bool visibility = (bool)value;
            return visibility ? Visibility.Visible : Visibility.Collapsed;
        }

        public object ConvertBack(
            object value,
            Type targetType,
            object parameter,
            CultureInfo culture)
        {
            Visibility visibility = (Visibility)value;
            return (visibility == Visibility.Visible);
        }
    }