title: Binding of a Polyline. What am I doing wrong?
body: <p>I am trying what I thought a simple thing: drawing lines of a list of point.
  If I put the list statically in the xaml of my window everything is ok.
  If I do the bind, then nothing is displayed.</p>
  
  <p>the window code:</p>
  
  <pre><code>&lt;Grid&gt;
      &lt;Grid.ColumnDefinitions&gt;
          &lt;ColumnDefinition Width="*" /&gt;
          &lt;ColumnDefinition Width="*" /&gt;
      &lt;/Grid.ColumnDefinitions&gt;
      &lt;Polyline Stretch="Fill" Grid.Column="0" Name="polyline" Stroke="Red" DataContext="{Binding Points}"&gt;
      &lt;/Polyline&gt;   
  &lt;/Grid&gt;
  </code></pre>
  
  
  
  <pre><code>public partial class testWindow2 : Window
  {
      AudioSignalModelView audioSignalModelView;
  
      public testWindow2()
      {
          InitializeComponent();
  
          audioSignalModelView = new AudioSignalModelView();
  
          this.DataContext = audioSignalModelView;
      }
  }
  
  public class AudioSignalModelView
  {
      public AudioSignalModelView()
      {
          Point pointA = new Point {X=0,Y=0};
          Point pointB = new Point { X = 0.2, Y = 0.4 };
          Point pointC = new Point { X = 0.8, Y = 0.1 };
          Point pointD = new Point { X = 1, Y = 1 };
  
          Points.Add(pointA);
          Points.Add(pointB);
          Points.Add(pointC);
          Points.Add(pointD);
      }
  
      private AudioSignalTest audioSignalTest;
  
      private PointCollection _points = new PointCollection();
      public PointCollection Points
      {
          get { return _points; }
      }
  }
  </code></pre>
  
  <p>I think the binding is done somehow, because if I put a breakpoint in the getter of the Points property, it is called by the system...</p>
  
  <p>What is obviously wrong in my code ? </p>