title: Bind width of a textbox inside VisualBrush
body: <p>I have a small issue that I can't seem to get right.
  I have a textbox where I'm adding "Search hint"</p>
  
  <p><img src="https://i.stack.imgur.com/Jvv0L.jpg" alt="enter image description here"></p>
  
  <p>I'm using this XAML snippet </p>
  
  <pre><code>&lt;TextBox x:Name="txtboxSearch" Height="22" Margin="3,35,111,0" TextWrapping="Wrap" VerticalAlignment="Top" BorderThickness="1" MaxLines="1" MaxLength="256" Grid.Column="2" BorderBrush="#FF828790"&gt;
          &lt;TextBox.Style&gt;
              &lt;Style TargetType="TextBox" xmlns:sys="clr-namespace:System;assembly=mscorlib"&gt;
                  &lt;Style.Resources&gt;
                      &lt;VisualBrush x:Key="CueBannerBrush" AlignmentX="Left" AlignmentY="Center" Stretch="None"&gt;
                          &lt;VisualBrush.Visual&gt;
                              &lt;TextBox Text="Search" Foreground="LightGray" FontStyle="Italic" /&gt;
                          &lt;/VisualBrush.Visual&gt;
                      &lt;/VisualBrush&gt;
                  &lt;/Style.Resources&gt;
                  &lt;Style.Triggers&gt;
                      &lt;Trigger Property="Text" Value="{x:Static sys:String.Empty}"&gt;
                          &lt;Setter Property="Background" Value="{StaticResource CueBannerBrush}" /&gt;
                      &lt;/Trigger&gt;
                      &lt;Trigger Property="Text" Value="{x:Null}"&gt;
                          &lt;Setter Property="Background" Value="{StaticResource CueBannerBrush}" /&gt;
                      &lt;/Trigger&gt;
                      &lt;Trigger Property="IsKeyboardFocused" Value="True"&gt;
                          &lt;Setter Property="Background" Value="White" /&gt;
                      &lt;/Trigger&gt;
                  &lt;/Style.Triggers&gt;
              &lt;/Style&gt;
          &lt;/TextBox.Style&gt;
      &lt;/TextBox&gt;
  </code></pre>
  
  <p>Because background of the window is not white I am getting a result as shown in picture. I tried to bind width multiple different ways, but nothing seem to work, can you please suggest?</p>
  
  <p>I want it to look like this 
  <img src="https://i.stack.imgur.com/K5Rym.jpg" alt="enter image description here"></p>
  
  <p>thank you!</p>