title: MahApps Progress Indicator not stretching to content
body: <p>I have a MahApps progress indicator declared like this:</p>
  
  <pre><code>&lt;Controls:ProgressIndicator ProgressColour="{StaticResource AccentColorBrush}" Width="600" Height="20" VerticalAlignment="Top" HorizontalAlignment="Stretch"
                                  Visibility="{Binding ElementName=Self, Path=DataContext.ShowProgress, Converter={StaticResource b2v}, FallbackValue=Visible}"/&gt;  
  </code></pre>
  
  <p>And for some reason the indicator bars do not stretch the size of the control. It only fills about 20% of the width. (I can't show a picture as my reputation is too low).</p>
  
  <p>Has anyone experienced this before?</p>
  
  <p>Cheers</p>
  
  <p><strong>Edit</strong></p>
  
  <p>The indicator is on a stackpanel declared like this:  </p>
  
  <pre><code>&lt;StackPanel Grid.Column="2" Grid.ColumnSpan="6" Orientation="Vertical"&gt;  
  </code></pre>