title: WPF Tooltip ControlTemplate not showing Content
body: <p>I have set up the following control template and style as the default style for all Tooltips in my application:</p>
  
  <pre><code>&lt;Style TargetType="{x:Type ToolTip}"&gt;
      &lt;!-- Background="Transparent" BorderBrush="Transparent" BorderThickness="0" HasDropShadow="True" --&gt;
      &lt;Setter Property="Background" Value="Transparent" /&gt;
      &lt;Setter Property="BorderBrush" Value="Transparent" /&gt;
      &lt;Setter Property="OverridesDefaultStyle" Value="true" /&gt;
      &lt;Setter Property="Placement" Value="Bottom"&gt;&lt;/Setter&gt;
      &lt;Setter Property="BorderThickness" Value="0" /&gt;
      &lt;Setter Property="Template"&gt;
          &lt;Setter.Value&gt;
              &lt;ControlTemplate&gt;
                  &lt;Grid Background="{Binding Source={x:Static visualResources:ThemeManager.Instance}, Path=ThemePageColor}" &gt;
                      &lt;ContentPresenter Margin="3"&gt;&lt;/ContentPresenter&gt;
                  &lt;/Grid&gt;
              &lt;/ControlTemplate&gt;
          &lt;/Setter.Value&gt;
      &lt;/Setter&gt;
  &lt;/Style&gt;
  </code></pre>
  
  <p>(The code above is in the Window.Resources)</p>
  
  <p>And inside the same window I have this control:</p>
  
  <pre><code>&lt;Button ToolTip="Tooltip Text!" HorizontalContentAlignment="Right" Height="60" Click="_Button_AddCourse_Click"/&gt;
  </code></pre>
  
  <p>But when I run my program the tooltips don't appear as they should! I Only can see an orange rectangle (which is the Grid in controltemplate , and orange is the ThemeManager.Instance.ThemePageColor property) , But there is no text inside the tooltip.</p>
  
  <p>Thanks in advance.</p>