Shaker/Avalonia/SukiUI.Dock/ToolControl.axaml

<ResourceDictionary xmlns="https://github.com/avaloniaui"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:dmc="using:Dock.Model.Controls"
                    xmlns:core="using:Dock.Model.Core">
  <Design.PreviewWith>
    <ToolControl Width="300" Height="400" />
  </Design.PreviewWith>

  <ControlTheme x:Key="{x:Type ToolControl}" TargetType="ToolControl">

    <Setter Property="HeaderTemplate">
      <DataTemplate DataType="core:IDockable">
        <TextBlock Text="{Binding Title}" Padding="2" />
      </DataTemplate>
    </Setter>

    <Setter Property="Template">
      <ControlTemplate>
 
        <DockPanel x:Name="PART_DockPanel"
                   DockProperties.IsDropArea="True"
                   DockProperties.IsDockTarget="True"
                   x:DataType="dmc:IToolDock"
                   x:CompileBindings="True">
          <ToolTabStrip x:Name="PART_TabStrip"
                        ItemsSource="{Binding VisibleDockables}"
                        SelectedItem="{Binding ActiveDockable, Mode=TwoWay}"
                        DockPanel.Dock="Bottom"
                        DockProperties.IsDropArea="True" />
          <Border x:Name="PART_Border">
            <DockableControl DataContext="{Binding ActiveDockable}"
                             TrackingMode="Visible">
              <ContentControl x:Name="PART_ContentPresenter"
                              Content="{Binding}"
                              HorizontalAlignment="Stretch"
                              VerticalAlignment="Stretch">
                <ContentControl.ContentTemplate>
                  <ControlRecyclingDataTemplate Parent="{Binding #PART_ContentPresenter}" />
                </ContentControl.ContentTemplate>
              </ContentControl>
            </DockableControl>
          </Border>
        </DockPanel>
       
      </ControlTemplate>
    </Setter>

    <Style Selector="^/template/ DockPanel#PART_DockPanel">
      <Setter Property="Background" Value="Transparent" />
      <Setter Property="ZIndex" Value="1" />
    </Style>

    <Style Selector="^/template/ Border#PART_Border">
      <Setter Property="ZIndex" Value="-1" />
      <Setter Property="Background" Value="{DynamicResource DockThemeBackgroundBrush}" />
      <Setter Property="Margin" Value="0" />
      <Setter Property="BorderBrush" Value="{DynamicResource DockThemeBorderLowBrush}" />
      <Setter Property="BorderThickness" Value="0" />
    </Style>

  </ControlTheme>

</ResourceDictionary>