Shaker/Avalonia/SukiUI.Dock/HostWindow.axaml

<ResourceDictionary xmlns="https://github.com/avaloniaui"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:core="using:Dock.Model.Core"
                    xmlns:controls="clr-namespace:Dock.Model.Controls;assembly=Dock.Model">
  <Design.PreviewWith>
    <HostWindow IsToolWindow="False" Width="300" Height="400" />
  </Design.PreviewWith>



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

    <Setter Property="Background" Value="Transparent" />
    <Setter Property="(TextElement.FontSize)" Value="{DynamicResource DockFontSizeNormal}" />
    <!-- <Setter Property="FontFamily" Value="{TemplateBinding FontFamily}" /> -->
    <Setter Property="TextBlock.Foreground" Value="{DynamicResource DockThemeForegroundBrush}" />
    <Setter Property="WindowState" Value="Normal" />
    <Setter Property="UseLayoutRounding" Value="True" />
    <Setter Property="Title" Value="{Binding ActiveDockable.Title}" />
    <Setter Property="Topmost" Value="{Binding Window.Topmost}" x:DataType="controls:IRootDock" />
    <Setter Property="SystemDecorations" Value="None" />
   <Setter Property="ExtendClientAreaToDecorationsHint" Value="True" />
    <Setter Property="ExtendClientAreaChromeHints" Value="NoChrome"/>
<Setter Property="ExtendClientAreaTitleBarHeightHint" Value="-1"></Setter>
    <Setter Property="Template">
      <ControlTemplate>
        <Panel>
          <Border Name="SelectedBorder" 
                  Margin="10,10"
                  Padding="0"
                  BoxShadow="{DynamicResource SukiPopupShadow}"
                  Background="{DynamicResource SukiCardBackground}"
                  CornerRadius="20">
            <Border CornerRadius="20" ClipToBounds="True">
              <Panel>
                <Panel Margin="0">
                  <Panel.Background>
                    <LinearGradientBrush StartPoint="0%,0%" EndPoint="100%,100%">
                      <GradientStop Color="{DynamicResource SukiAccentColor5}" Offset="0"></GradientStop>
                      <GradientStop Color="{DynamicResource SukiPrimaryColor5}" Offset="1"></GradientStop>
                    </LinearGradientBrush>
                  </Panel.Background>
                </Panel>
              </Panel>
            </Border>
          </Border>
          <Border Name="PART_TransparencyFallback" IsHitTestVisible="False" />
          <Border Background="{TemplateBinding Background}" IsHitTestVisible="False" />
          <Panel Background="Transparent" Margin="{TemplateBinding WindowDecorationMargin}" />
          <VisualLayerManager>
            <VisualLayerManager.ChromeOverlayLayer>
              <HostWindowTitleBar Name="PART_TitleBar" />
            </VisualLayerManager.ChromeOverlayLayer>
            <ContentPresenter Name="PART_ContentPresenter"
                              ContentTemplate="{TemplateBinding ContentTemplate}"
                              Content="{TemplateBinding Content}"
                              Margin="{TemplateBinding Padding}"
                              HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
                              VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" />
          </VisualLayerManager>
        </Panel>
      </ControlTemplate>
    </Setter>

    <Setter Property="Content">
      <Template>
        <Panel Margin="{Binding $parent[HostWindow].OffScreenMargin}">
          <Panel Margin="{Binding $parent[HostWindow].WindowDecorationMargin}">
            <DockControl Layout="{Binding}"
                         x:DataType="core:IHostWindow"
                         x:CompileBindings="True" />
          </Panel>
        </Panel>
      </Template>
    </Setter>

 
   

  </ControlTheme>

</ResourceDictionary>