Databinding WPF Rectangle gradient fill

I'm attempting to databind a gradient brush as a Rectangle fill. What do I need to do to get the commented-out binding to work? 开发者_开发问答StartColor and EndColor are declared as System.Drawing.Color.

<Rectangle Width="100" Height="20">
  <Rectangle.Fill>
    <LinearGradientBrush>
      <GradientStop Offset="0" Color="Pink"/>
      <GradientStop Offset="1"  Color="Red"/>
      <!--<GradientStop Offset="0" Color="{Binding Path=StartColor}"/>-->
      <!--<GradientStop Offset="1" Color="{Binding Path=EndColor}" />-->
    </LinearGradientBrush>
  </Rectangle.Fill>
</Rectangle>

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The problem was using System.Drawing.Color rather than the proper System.Windows.Media.Color