Did You Know That… You can get sharp lines within a linear gradient?

This tip is thanks to Adam Nathan and his excellent book Silverlight 1.0 Unleashed

Silverlight 1.0 Unleashed
by Adam Nathan

You can achieve the startling effect of introducing sharp lines within a linear gradient by adding two GradientStops at the same offset, using different, and reinforcing colors. In the following example, I show two polygons. The first uses a standard gradient brush, but in the second I introduce a new color (DarkBlue) which I place at the same GradientStop as Green and at the same GradientStop as Blue. The effect is quite unmistakable, as shown in the image.

<Canvas xmlns="http://schemas.microsoft.com/client/2007" 
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Polygon x:Name="PolyWithGradientBrush"
         Points= "50,70, 100,70, 150,120, 150,170, 100,220, 
         50,220, 0,170, 0,120, 50,70"
         StrokeThickness="2"
         Stroke="Black" >
  <Polygon.Fill>
         <LinearGradientBrush>
            <GradientStop Color="Red"
                          Offset="0.0" />
            <GradientStop Color="Orange"
                          Offset="0.3" />
            <GradientStop Color="Green"
                          Offset="0.5" />
            <GradientStop Color="Blue"
                          Offset="0.7" />
            <GradientStop Color="Violet"
                          Offset="1.0" />
         </LinearGradientBrush>
      </Polygon.Fill>
</Polygon>

   <Polygon x:Name="PolyWithGradientBrushAndSharpLines"
            Points="250,70, 300,70, 350,120, 350,170, 300,220, 
         250,220, 200,170, 200,120, 250,70"
            StrokeThickness="2"
            Stroke="Black">
      <Polygon.Fill>
         <LinearGradientBrush>
            <GradientStop Color="Red"
                          Offset="0.0" />
            <GradientStop Color="Orange"
                          Offset="0.3" />
            <GradientStop Color="Green"
                          Offset="0.5" />
            <GradientStop Color="DarkBlue"
                          Offset="0.5" />
            <GradientStop Color="DarkBlue"
                          Offset="0.7" />
            <GradientStop Color="Blue"
                          Offset="0.7" />
            <GradientStop Color="Violet"
                          Offset="1.0" />
         </LinearGradientBrush>
      </Polygon.Fill>
   </Polygon>
</Canvas>