// System.Windows.Markup.XamlWriter
public static string Save(object obj)
{
    SecurityHelper.DemandUnmanagedCode();
    if (obj == null)
    {
        throw new ArgumentNullException("obj");
    }
    StringBuilder stringBuilder = new StringBuilder();
    TextWriter textWriter = new StringWriter(stringBuilder, TypeConverterHelper.EnglishUSCulture);
    try
    {
        XamlWriter.Save(obj, textWriter);
    }
    finally
    {
        textWriter.Close();
    }
    return stringBuilder.ToString();
}

------解决方案--------------------
用反编译工具 .NET Reflector

------解决方案--------------------
我一般用.NET Reflector 看。