title: Datepicker button does not appear
body: <p>I am trying to design layout of my WPF windows to add some code list item and I need to use DatePicker, but calendar button is not visible in textbox.</p>
  
  <p>this is my grid:</p>
  
  <pre><code>&lt;Grid&gt;
          &lt;Grid.RowDefinitions&gt;
              &lt;RowDefinition Height="35"&gt;&lt;/RowDefinition&gt;
              &lt;RowDefinition Height="35"&gt;&lt;/RowDefinition&gt;
              &lt;RowDefinition Height="*"&gt;&lt;/RowDefinition&gt;
          &lt;/Grid.RowDefinitions&gt;
  
          &lt;Grid.ColumnDefinitions&gt;
              &lt;ColumnDefinition Width="auto"&gt;&lt;/ColumnDefinition&gt;
              &lt;ColumnDefinition Width="*"&gt;&lt;/ColumnDefinition&gt;
              &lt;ColumnDefinition Width="auto"&gt;&lt;/ColumnDefinition&gt;
              &lt;ColumnDefinition Width="*"&gt;&lt;/ColumnDefinition&gt;
          &lt;/Grid.ColumnDefinitions&gt;
  
          &lt;Label Content="Code" Grid.Column="0" Grid.Row="0" /&gt;
          &lt;TextBox Text="{Binding Path=Code}" Grid.Column="1" Grid.Row="0" MinWidth="160" MaxLength="30" MaxWidth="160" /&gt;
  
          &lt;Label Content="Description" Grid.Column="0" Grid.Row="1" /&gt;
          &lt;TextBox Text="{Binding Path=Description}" Grid.Column="1" Grid.Row="1" MinWidth="160" MaxLength="120" MaxWidth="160" /&gt;
  
          &lt;Label Content="Valid from" Grid.Column="2" Grid.Row="0" /&gt;
          &lt;DatePicker Name="dpValidFrom" VerticalAlignment="Top" Grid.Column="3" Grid.Row="0" /&gt;
  
          &lt;Label Content="Valid to" Grid.Column="2" Grid.Row="1" /&gt;
          &lt;DatePicker Name="dpValidTo" VerticalAlignment="Top" Grid.Column="3" Grid.Row="1" /&gt;
      &lt;/Grid&gt;
  </code></pre>
  
  <p>In design mode a see this:</p>
  
  <p><a href="https://i.stack.imgur.com/PCydT.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/PCydT.png" alt="In design mode a see this"></a></p>
  
  <p>but in app i see this:
  <a href="https://i.stack.imgur.com/4n0E5.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/4n0E5.png" alt="but in app i see this"></a></p>
  
  <p>have someone idea why?
  Thanks for advice</p>