title: MultiTrigger not working When Validation.HasError and IsMouseOver in WPF
body: <p>I have this <code>TextBox</code> :</p>
  
  <pre><code>&lt;TextBox IsEnabled="{Binding IsChecked, ElementName=Cb_AllowDeletingPictures}"
                   Style="{DynamicResource TextBoxInError}"&gt;
       &lt;TextBox.Text&gt;
            &lt;Binding Path="TimeBeforeDeletingPicture" Mode="TwoWay" UpdateSourceTrigger="PropertyChanged"&gt;
                 &lt;Binding.ValidationRules&gt;
                      &lt;helpers:TimeBeforeDeletingRule/&gt;
                 &lt;/Binding.ValidationRules&gt;
            &lt;/Binding&gt;
       &lt;/TextBox.Text&gt;
  &lt;/TextBox&gt;
  </code></pre>
  
  <p>The <code>TextBoxInError</code> Style contains a Template for the <code>Validation.ErrorTemplate</code> property and a <code>MultiTrigger</code> that sets a tooltip and turns the <code>BorderBrush</code> and the <code>Foreground</code> to red, this is how it looks like :</p>
  
  <pre><code>&lt;Style x:Key="TextBoxInError" TargetType="{x:Type TextBox}"&gt;
          &lt;Setter Property="Validation.ErrorTemplate"&gt;
              &lt;Setter.Value&gt;
                  &lt;ControlTemplate&gt;
                      &lt;DockPanel&gt;
                          &lt;TextBlock Foreground="Red" FontSize="20" FontWeight="Bold" Text="!" FontFamily="Segoe UI Light"&gt;&lt;/TextBlock&gt;
                          &lt;AdornedElementPlaceholder/&gt;
                      &lt;/DockPanel&gt;
                  &lt;/ControlTemplate&gt;
              &lt;/Setter.Value&gt;
          &lt;/Setter&gt;
          &lt;Style.Triggers&gt;
              &lt;MultiTrigger&gt;
                  &lt;MultiTrigger.Conditions&gt;
                      &lt;Condition Property="Validation.HasError" Value="True"&gt;&lt;/Condition&gt;
                      &lt;Condition Property="IsMouseOver" Value="True"&gt;&lt;/Condition&gt;
                  &lt;/MultiTrigger.Conditions&gt;
                  &lt;Setter Property="Foreground" Value="Red" /&gt;
                  &lt;Setter Property="BorderBrush" Value="Red"/&gt;
                  &lt;Setter Property="ToolTip"
                      Value="{Binding (Validation.Errors)[0].ErrorContent, RelativeSource={x:Static RelativeSource.Self}}"/&gt;
              &lt;/MultiTrigger&gt;
          &lt;/Style.Triggers&gt;
  &lt;/Style&gt;
  </code></pre>
  
  <p>Now, as you can see in the next screenshot, the ErrorTemplate works just fine showing a red exclamation mark before the TextBox, the problem is that :</p>
  
  <ul>
  <li>When the Mouse <code>is not over</code> the TextBox, neither the Foreground nor the the BorderBrush are red, which is just ok.</li>
  <li>Now when the Mouse <code>is over</code> the area of the TextBox, only the Foreground turns red, while the BorderBrush keeps its original behavior when the Mouse is over it. </li>
  </ul>
  
  <p><strong>When the Mouse is not over the TextBox area :</strong></p>
  
  <p><img src="https://i.stack.imgur.com/Oom2X.png" alt="When not MouseOver"></p>
  
  <p><strong>When the Mouse is over the TextBox area :</strong></p>
  
  <p><img src="https://i.stack.imgur.com/r5Usn.png" alt="When isMouseOver"></p>
  
  <p>Why there is such a behavior, why is it working fot the Foreground and not for the BorderBrush ? Am I missing something ?</p>