title: WPF Databinding StringFormat does not support hex format?
body: <p>I am using WPF databinding. I can format the number if I specify <code>StringFormat={}{0:C}</code>. However, if I use <code>StringFormat={}{0:X2}</code>, it will give give the following exception:</p>
  
  <pre><code>System.Windows.Data Error: 6 : 'StringFormat' converter failed to convert value '10' (type 'Double'); fallback value will be used, if available. BindingExpression:Path=Value; DataItem='Slider' (Name='SliderG'); target element is 'TextBlock' (Name=''); target property is 'Text' (type 'String') FormatException:'System.FormatException: Format specifier was invalid.
     at System.Number.FormatDouble(Double value, String format, NumberFormatInfo info)
     at System.Double.ToString(String format, IFormatProvider provider)
     at System.Text.StringBuilder.AppendFormat(IFormatProvider provider, String format, Object[] args)
     at System.String.Format(IFormatProvider provider, String format, Object[] args)
     at System.Windows.Data.BindingExpression.ConvertHelper(IValueConverter converter, Object value, Type targetType, Object parameter, CultureInfo culture)'
  'WpfApplication1.vshost.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Numerics\v4.0_4.0.0.0__b77a5c561934e089\System.Numerics.dll', Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
  </code></pre>
  
  <p>Anyone gets any idea?</p>