WPF – Add the horizontal line to the Silverlight Toolkit column chart

I use Silverlight Toolkit in a WPF project, and I want to set the Y-axis value that I can specify Add a red dashed horizontal line to the column chart. I have modified the chart template and successfully added a row, but I don’t know how to make the row display at the y-axis value I want and how to make it expand throughout the chart. This is The chart picture I have so far:

This is the XAML code of the chart template I used to generate it:

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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Does anyone know how to do this?

Thanks,
Paul

By the way, I created a more general chart that can handle any type of series (Column, Bar, StackedColumn, etc.), and display any value as a line.

I explained the usage of this chart in a blog post.

The source code can be downloaded Go here.