title: Two LineSeries with the same Y Axis in WPF Toolkit charts
body: <p>I want to do the following with the WPF toolkit charts:</p>
  
  <p>I have two line series that should use the same y axis (i.e I want them both to be on the same scale).  I could give each of them the same axis definition so they would overlap (and then have one of them with collapsed visibility), but that is not my best choice.</p>
  
  <p>This is the solution I'm talking about:</p>
  
  <pre><code>&lt;charts:LineSeries Name="ExternalMeasureSeries"
                 IndependentValueBinding="{Binding Time}"
                 DependentValueBinding="{Binding ExternalMeasure}"&gt;
      &lt;charts:LineSeries.DataPointStyle&gt;
          &lt;Style TargetType="charts:LineDataPoint"&gt;
              &lt;Setter Property="Background" Value="Red"/&gt;
              &lt;Setter Property="Opacity" Value="0" /&gt;
          &lt;/Style&gt;
      &lt;/charts:LineSeries.DataPointStyle&gt;
      &lt;!-- Vertical axis for external measure curve --&gt;
      &lt;charts:LineSeries.DependentRangeAxis&gt;
          &lt;charts:LinearAxis
              Orientation="Y"
              Title="Measurement"
              Minimum="0"
              Maximum="30"/&gt;
      &lt;/charts:LineSeries.DependentRangeAxis&gt;
  &lt;/charts:LineSeries&gt;
  &lt;charts:LineSeries Name="InternalMeasureSeries"
                     IndependentValueBinding="{Binding Time}"
                     DependentValueBinding="{Binding InternalMeasure}"&gt;
      &lt;charts:LineSeries.DataPointStyle&gt;
          &lt;Style TargetType="charts:LineDataPoint"&gt;
              &lt;Setter Property="Background" Value="Orange"/&gt;
              &lt;Setter Property="Opacity" Value="0" /&gt;
          &lt;/Style&gt;
      &lt;/charts:LineSeries.DataPointStyle&gt;
      &lt;!-- Vertical axis for internal measure curve --&gt;
      &lt;charts:LineSeries.DependentRangeAxis&gt;
          &lt;charts:LinearAxis
              Orientation="Y"
              Minimum="0"
              Maximum="30"
              Visibility="Collapsed"/&gt;
      &lt;/charts:LineSeries.DependentRangeAxis&gt;
  &lt;/charts:LineSeries&gt;
  </code></pre>
  
  <p>Is there a way to define more than one series with the same Y axis?</p>
  
  <p>I found that toolkit version 3.5.0.0 has something called <code>StackedLineSeries</code> but that version 3.5.40128.1 which is what gets installed in the February 2010 version of the toolkit, it isn't there.  Did it move to another clr-namespace?</p>