WPF

      var binding = new Binding();
      binding.Source = DictThresholds;
      binding.Converter = new DictionaryLookupConverter();
      binding.ConverterParameter = thresholdKey;
      newThresholdLine.SetBinding(HorizontalLine.ValueProperty, binding);

class DictionaryLookupConverter : IValueConverter
{
  public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
  {
    object result;
    IDictionary dict = value as IDictionary;
    if (dict == null || parameter == null || !dict.TryGetValue(parameter, out result))
    {
      return DependencyProperty.UnsetValue;
    }
    return result;
  }
}

''' <summary>
 ''' Set binding from Double property to TextBox.Text
 ''' </summary>
 ''' <param name="Source">The class instance</param>
 ''' <param name="Path">Property name in the class</param>
 ''' <param name="control">The textboxcontrol</param>
 ''' <remarks></remarks>
 Sub SetObjectBinding(ByVal Source As Object, ByVal Path As String, ByVal control As TextBox)
     Dim bnd As New Binding
     bnd.Path = New PropertyPath(Path)
     bnd.Source = Source
     bnd.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged
     bnd.Converter = New DoubleToStringConverter
     bnd.ValidationRules.Add(New PositiveDoubleValidator)
     control.SetBinding(TextBox.TextProperty, bnd)
 End Sub

<ValueConversion(GetType(Double), GetType(String))>
Private Class DoubleToStringConverter
    Implements IValueConverter

    Public Function Convert(value As Object, targetType As System.Type, parameter As Object, culture As System.Globalization.CultureInfo) As Object Implements System.Windows.Data.IValueConverter.Convert
        Return value.ToString
    End Function

    Public Function ConvertBack(value As Object, targetType As System.Type, parameter As Object, culture As System.Globalization.CultureInfo) As Object Implements System.Windows.Data.IValueConverter.ConvertBack
        Dim d As Double
        Dim str As String = value.ToString

        If str.Contains(".") Then str = str.Replace(".", ",")

        If Double.TryParse(str, d) Then
            If d > 0 Then
                Return d
            Else
                Return DependencyProperty.UnsetValue
            End If
        End If

        Return value.ToString
    End Function
End Class

Public Class PositiveDoubleValidator
    Inherits ValidationRule

    Public Overloads Overrides Function Validate(value As Object, cultureInfo As System.Globalization.CultureInfo) As System.Windows.Controls.ValidationResult

        Dim d As Double
        Dim str As String = value.ToString

        If str.Contains(".") Then str = str.Replace(".", ",")
        If Double.TryParse(str, d) Then
            If d > 0 Then
                Return ValidationResult.ValidResult
            Else
                Return New ValidationResult(False, "The entered value must be positive")
            End If
        Else
            Return New ValidationResult(False, "The value '" & str & "' could not be converted to a positive number")
        End If

    End Function
End Class

<Style TargetType="{x:Type TextBox}">
    <Setter Property="Validation.ErrorTemplate">
        <Setter.Value>
            <ControlTemplate>
                <DockPanel LastChildFill="True">
                    <Border BorderBrush="Red" BorderThickness="5">
                        <AdornedElementPlaceholder />
                    </Border>
                </DockPanel>
            </ControlTemplate>
        </Setter.Value>
    </Setter>