IValueConveyor

IValueConverter

[ValueConversion(typeof(Visibility), typeof(string))]
public class VisibilityStringConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        Visibility visibility = (Visibility)value;
        return visibility.ToString();
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        string visibility = value.ToString().ToLower();
        Visibility result = Visibility.Collapsed;
        if (visibility == "true" || visibility == "visible")
        {
            result = Visibility.Visible;
        }
        return result;
    }
}

[ValueConversion(typeof(string), typeof(Visibility))]
public class StringVisibilityConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        string visibility = value.ToString();
        Visibility result = Visibility.Collapsed;
        if (visibility == "true" || visibility == "visible")
        {
            result = Visibility.Visible;
        }
        return result;
    }

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

StaticResource

xmlns:Converters="clr-namespace:PMTW.PMOP.WPF.SolutionExplorer.Converters"

<Converters:VisibilityStringConverter x:Key="VisibilityStringConverter"/>
<Converters:StringVisibilityConverter x:Key="StringVisibilityConverter"/>

<CheckBox Content="&#x2713;" Foreground="White" IsEnabled="False" 
            Template="{StaticResource CheckBoxTemplate}"
            IsChecked="{Binding Path=Element[IsLoaded].Value}" Visibility="{Binding Path=Element[IsLoaded].Value, Converter={StaticResource StringVisibilityConverter}}"/>