title: Images are not sharp in selected TabItem
body: <p>I have a TabControl. The header of each TabItem contains a StackPanel with an icon and a Label.</p>
  
  <pre><code>&lt;TabControl&gt;
    &lt;TabItem&gt;
      &lt;TabItem.Header&gt;
        &lt;StackPanel Orientation="Horizontal"&gt;
          &lt;Image Source="/LoginPanel;component/Icons/icoLogin.ico"&lt;/Image&gt;
          &lt;Label VerticalContentAlignment="Center"&gt;Login&lt;/Label&gt;
          &lt;/StackPanel&gt;
        &lt;/TabItem.Header&gt;
      &lt;/TabItem.Header&gt;
      &lt;!--some further code here--&gt;
    &lt;TabItem&gt;
    &lt;!--some further code here--&gt;
  &lt;TabControl&gt;
  </code></pre>
  
  <p>Each icon in each non-selected TabItem is displayed as expected. The Icon in the currently selected TabItem is somewhat cloudy. If I switch to another Tab, the de-selected Tab-Icon becomes clear; the new selected Icon becomes cloudy.</p>
  
  <p>I already tried the following to solve this:</p>
  
  <pre><code>SnapsToDevicePixels="True"
  </code></pre>
  
  <p>but nothing happens</p>
  
  <p>or</p>
  
  <pre><code>Width="32" Height="32"
  </code></pre>
  
  <p>or</p>
  
  <pre><code>Stretch="None"
  </code></pre>
  
  <p>to prevent scaling.
  All of this without any effect. Can some please give me a hint? Thanks in advance</p>