Change Line thickness for selected feature set

Using XAML in a viewer.xml (or altering a theme) we can control the boundary color and fill color of selected features in a viewer.  

We also need the ability to control the line thickness of selected features.

Example xaml - this needs to also include an option for Line thickness.  

    <Xaml>
      <ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:System="clr-namespace:System;assembly=mscorlib">
        <Color x:Key="SelectionFillColor">#00FFFFFF</Color>
        <Color x:Key="SelectionBorderColor">#FFFF0000</Color>
      </ResourceDictionary>
    </Xaml>