///--------------------------------------------------------------------
/// <summary>
/// Gets the current property values from target.
/// </summary>
/// <param name="rangeValuePattern">
/// A RangeValuePattern control pattern obtained from 
/// an automation element representing a target control.
/// </param>
/// <param name="automationProperty">
/// The automation property of interest.
/// </param>
///--------------------------------------------------------------------
private object GetRangeValueProperty(
    RangeValuePattern rangeValuePattern,
    AutomationProperty automationProperty)
{
    if (rangeValuePattern == null || automationProperty == null)
    {
        throw new ArgumentException("Argument cannot be null.");
    }

    if (automationProperty.Id ==
        RangeValuePattern.MinimumProperty.Id)
    {
        return rangeValuePattern.Current.Minimum;
    }
    if (automationProperty.Id ==
        RangeValuePattern.MaximumProperty.Id)
    {
        return rangeValuePattern.Current.Maximum;
    }
    if (automationProperty.Id ==
        RangeValuePattern.SmallChangeProperty.Id)
    {
        return rangeValuePattern.Current.SmallChange;
    }
    if (automationProperty.Id ==
        RangeValuePattern.LargeChangeProperty.Id)
    {
        return rangeValuePattern.Current.LargeChange;
    }
    if (automationProperty.Id ==
        RangeValuePattern.ValueProperty.Id)
    {
        return rangeValuePattern.Current.Value;
    }
    return null;
}