title: Global style can't be overridden
body: <p>I have this defined in my app.xaml</p>
  
  <pre><code>&lt;Style TargetType="{x:Type TextBlock}"&gt;
      &lt;Setter Property="FontSize" Value="12"&gt;&lt;/Setter&gt;
      &lt;Setter Property="FontFamily" Value="Cailibri"&gt;&lt;/Setter&gt;
  &lt;/Style&gt;
  </code></pre>
  
  <p>and this defined in Window1.xaml</p>
  
  <pre><code>&lt;Style x:Key="BASE"&gt;
              &lt;Setter Property="Control.FontSize"  Value="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=Window}, Path=MyFontSize}"&gt;
              &lt;/Setter&gt;
              &lt;Setter Property="Control.FontFamily"  Value="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=Window}, Path=MyFontFamily}"&gt;
              &lt;/Setter&gt;
              &lt;Setter Property="Control.HorizontalAlignment"  Value="Left"&gt;
              &lt;/Setter&gt;
          &lt;/Style&gt;
  
  &lt;Style TargetType="{x:Type TextBlock}" BasedOn="{StaticResource BASE}"&gt;
          &lt;/Style&gt;
  
  &lt;Style TargetType="lc:LayoutItem" BasedOn="{StaticResource BASE}"&gt;
              &lt;Setter Property="LabelStyle"&gt;
                  &lt;Setter.Value&gt;
                      &lt;Style TargetType="lc:LayoutItemLabel" BasedOn="{StaticResource BASE}"&gt;
                      &lt;/Style&gt;
                  &lt;/Setter.Value&gt;
              &lt;/Setter&gt;
          &lt;/Style&gt;
  
  &lt;lc:LayoutControl x:Name="HeadLayout" lc:LayoutControl.CustomizationLabel="test"     ItemInsertionPointIndicatorStyle="{StaticResource myInsertionPointIndicator}"   HorizontalAlignment="Stretch" VerticalAlignment="Stretch"
                        AllowNewItemsDuringCustomization="False" AllowAvailableItemsDuringCustomization="True" Orientation="Horizontal"&gt;
  &lt;lc:LayoutGroup Orientation="Vertical" View="Group"   Margin="0,0,0,0"        HorizontalAlignment="Stretch" VerticalAlignment="Top"&gt;
  &lt;lc:LayoutItem Label=" CDFEG " x:Name="StoreName" &gt;
     &lt;TextBlock TextWrapping="Wrap" Text="ABCDEFG"/&gt;
     &lt;/lc:LayoutItem&gt;
   &lt;/lc:LayoutGroup&gt;
  &lt;/lc:LayoutControl&gt;
  </code></pre>
  
  <p>when i change the fontsize or fontfamily property , it works fine when TextBlock isn't defined in app.xaml.  I've searched this for a long time , but there's not quite a solution to me.  any advice will help, thx.</p>