chore: add avalonia TabControl demo.

src/Avalonia/HandyControlDemo_Avalonia/UserControl/Main/LeftMainContent.axaml

@@ -14,7 +14,7 @@
                 BorderThickness="0"
                 Background="{DynamicResource SecondaryRegionBrush}" />
         <TabControl BorderThickness="0 1 0 0"
-                    Classes="inline"
+                    Theme="{StaticResource TabControlInLine}"
                     SelectionChanged="TabControl_OnSelectionChanged"
                     ItemsSource="{Binding DemoInfoCollection}"
                     Background="Transparent"

src/Avalonia/HandyControlDemo_Avalonia/UserControl/Styles/NativeTabControlDemo.axaml

@@ -0,0 +1,189 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             x:Class="HandyControlDemo.UserControl.NativeTabControlDemo"
+             xmlns:hc="https://handyorg.github.io/handycontrol">
+    <ScrollViewer>
+        <hc:UniformSpacingPanel Margin="32"
+                                Spacing="32"
+                                ItemWidth="400"
+                                ItemHeight="200"
+                                MaxWidth="832"
+                                ChildWrapping="Wrap">
+            <TabControl TabStripPlacement="Right">
+                <TabItem Header="Title1">
+                    <Border>
+                        <TextBlock Theme="{StaticResource TextBlockLargeBold}">
+                            <Run Text="Text" />
+                            <Run Text="1" />
+                        </TextBlock>
+                    </Border>
+                </TabItem>
+                <TabItem Header="Title2"
+                         IsEnabled="False">
+                    <Border>
+                        <TextBlock Theme="{StaticResource TextBlockLargeBold}">
+                            <Run Text="Text" />
+                            <Run Text="2" />
+                        </TextBlock>
+                    </Border>
+                </TabItem>
+                <TabItem Header="Title3">
+                    <Border>
+                        <TextBlock Theme="{StaticResource TextBlockLargeBold}">
+                            <Run Text="Text" />
+                            <Run Text="3" />
+                        </TextBlock>
+                    </Border>
+                </TabItem>
+                <TabItem Header="Title4">
+                    <Border>
+                        <TextBlock Theme="{StaticResource TextBlockLargeBold}">
+                            <Run Text="Text" />
+                            <Run Text="4" />
+                        </TextBlock>
+                    </Border>
+                </TabItem>
+                <TabItem Header="Title5">
+                    <Border>
+                        <TextBlock Theme="{StaticResource TextBlockLargeBold}">
+                            <Run Text="Text" />
+                            <Run Text="5" />
+                        </TextBlock>
+                    </Border>
+                </TabItem>
+            </TabControl>
+            <TabControl Theme="{StaticResource TabControlInLine}">
+                <TabItem Header="Title1">
+                    <Border>
+                        <TextBlock Theme="{StaticResource TextBlockLargeBold}">
+                            <Run Text="Text" />
+                            <Run Text="1" />
+                        </TextBlock>
+                    </Border>
+                </TabItem>
+                <TabItem Header="Title2">
+                    <Border>
+                        <TextBlock Theme="{StaticResource TextBlockLargeBold}">
+                            <Run Text="Text" />
+                            <Run Text="2" />
+                        </TextBlock>
+                    </Border>
+                </TabItem>
+                <TabItem Header="Title3">
+                    <Border>
+                        <TextBlock Theme="{StaticResource TextBlockLargeBold}">
+                            <Run Text="Text" />
+                            <Run Text="3" />
+                        </TextBlock>
+                    </Border>
+                </TabItem>
+                <TabItem Header="Title4">
+                    <Border>
+                        <TextBlock Theme="{StaticResource TextBlockLargeBold}">
+                            <Run Text="Text" />
+                            <Run Text="4" />
+                        </TextBlock>
+                    </Border>
+                </TabItem>
+                <TabItem Header="Title5"
+                         IsSelected="True">
+                    <Border>
+                        <TextBlock Theme="{StaticResource TextBlockLargeBold}">
+                            <Run Text="Text" />
+                            <Run Text="5" />
+                        </TextBlock>
+                    </Border>
+                </TabItem>
+            </TabControl>
+            <TabControl TabStripPlacement="Left"
+                        Theme="{StaticResource TabControlCapsule}">
+                <TabItem Header="Title1">
+                    <Border>
+                        <TextBlock Theme="{StaticResource TextBlockLargeBold}">
+                            <Run Text="Text" />
+                            <Run Text="1" />
+                        </TextBlock>
+                    </Border>
+                </TabItem>
+                <TabItem IsSelected="True"
+                         Header="Title2">
+                    <Border>
+                        <TextBlock Theme="{StaticResource TextBlockLargeBold}">
+                            <Run Text="Text" />
+                            <Run Text="2" />
+                        </TextBlock>
+                    </Border>
+                </TabItem>
+                <TabItem Header="Title3">
+                    <Border>
+                        <TextBlock Theme="{StaticResource TextBlockLargeBold}">
+                            <Run Text="Text" />
+                            <Run Text="3" />
+                        </TextBlock>
+                    </Border>
+                </TabItem>
+                <TabItem Header="Title4">
+                    <Border>
+                        <TextBlock Theme="{StaticResource TextBlockLargeBold}">
+                            <Run Text="Text" />
+                            <Run Text="4" />
+                        </TextBlock>
+                    </Border>
+                </TabItem>
+                <TabItem Header="Title5">
+                    <Border>
+                        <TextBlock Theme="{StaticResource TextBlockLargeBold}">
+                            <Run Text="Text" />
+                            <Run Text="5" />
+                        </TextBlock>
+                    </Border>
+                </TabItem>
+            </TabControl>
+            <TabControl TabStripPlacement="Bottom"
+                        Theme="{StaticResource TabControlCapsuleSolid}">
+                <TabItem Header="Title1">
+                    <Border>
+                        <TextBlock Theme="{StaticResource TextBlockLargeBold}">
+                            <Run Text="Text" />
+                            <Run Text="1" />
+                        </TextBlock>
+                    </Border>
+                </TabItem>
+                <TabItem IsEnabled="False"
+                         Header="Title2">
+                    <Border>
+                        <TextBlock Theme="{StaticResource TextBlockLargeBold}">
+                            <Run Text="Text" />
+                            <Run Text="2" />
+                        </TextBlock>
+                    </Border>
+                </TabItem>
+                <TabItem Header="Title3">
+                    <Border>
+                        <TextBlock Theme="{StaticResource TextBlockLargeBold}">
+                            <Run Text="Text" />
+                            <Run Text="3" />
+                        </TextBlock>
+                    </Border>
+                </TabItem>
+                <TabItem IsSelected="True"
+                         Header="Title4">
+                    <Border>
+                        <TextBlock Theme="{StaticResource TextBlockLargeBold}">
+                            <Run Text="Text" />
+                            <Run Text="4" />
+                        </TextBlock>
+                    </Border>
+                </TabItem>
+                <TabItem Header="Title5">
+                    <Border>
+                        <TextBlock Theme="{StaticResource TextBlockLargeBold}">
+                            <Run Text="Text" />
+                            <Run Text="5" />
+                        </TextBlock>
+                    </Border>
+                </TabItem>
+            </TabControl>
+        </hc:UniformSpacingPanel>
+    </ScrollViewer>
+</UserControl>

src/Avalonia/HandyControlDemo_Avalonia/UserControl/Styles/NativeTabControlDemo.axaml.cs

@@ -0,0 +1,10 @@
+namespace HandyControlDemo.UserControl;
+
+public partial class NativeTabControlDemo : Avalonia.Controls.UserControl
+{
+    public NativeTabControlDemo()
+    {
+        InitializeComponent();
+    }
+}
+

src/Avalonia/HandyControl_Avalonia/Controls/Attach/ItemsControlAttach.cs

@@ -0,0 +1,71 @@
+using Avalonia;
+using Avalonia.Controls;
+using HandyControl.Tools;
+
+namespace HandyControl.Controls;
+
+public class ItemsControlAttach
+{
+    public static readonly AttachedProperty<ThemeSelector?> ItemsContainerThemeSelectorProperty =
+        AvaloniaProperty.RegisterAttached<ItemsControlAttach, AvaloniaObject, ThemeSelector?>(
+            "ItemsContainerThemeSelector");
+
+    public static void SetItemsContainerThemeSelector(AvaloniaObject element, ThemeSelector? value) =>
+        element.SetValue(ItemsContainerThemeSelectorProperty, value);
+
+    public static ThemeSelector? GetItemsContainerThemeSelector(AvaloniaObject element) =>
+        element.GetValue(ItemsContainerThemeSelectorProperty);
+
+    static ItemsControlAttach()
+    {
+        ItemsContainerThemeSelectorProperty.Changed.AddClassHandler<AvaloniaObject>(
+            OnItemsContainerThemeSelectorChanged);
+    }
+
+    private static void OnItemsContainerThemeSelectorChanged(AvaloniaObject element, AvaloniaPropertyChangedEventArgs e)
+    {
+        if (element is not ItemsControl itemsControl)
+        {
+            return;
+        }
+
+        itemsControl.ContainerPrepared -= OnContainerPrepared;
+        var themeSelector = e.GetNewValue<ThemeSelector?>();
+
+        if (themeSelector is null)
+        {
+            return;
+        }
+
+        itemsControl.ContainerPrepared += OnContainerPrepared;
+        ApplyTheme(itemsControl, themeSelector);
+    }
+
+    private static void OnContainerPrepared(object? sender, ContainerPreparedEventArgs e)
+    {
+        if (sender is not ItemsControl itemsControl)
+        {
+            return;
+        }
+
+        var themeSelector = GetItemsContainerThemeSelector(itemsControl);
+        if (themeSelector is null)
+        {
+            return;
+        }
+
+        ApplyTheme(itemsControl, themeSelector);
+    }
+
+    private static void ApplyTheme(ItemsControl itemsControl, ThemeSelector themeSelector)
+    {
+        for (int i = 0; i < itemsControl.ItemCount; i++)
+        {
+            var container = itemsControl.ContainerFromIndex(i);
+            if (container != null)
+            {
+                container.Theme = themeSelector.SelectTheme(itemsControl.Items[i], container);
+            }
+        }
+    }
+}

src/Avalonia/HandyControl_Avalonia/Controls/Attach/TitleElement.cs

@@ -5,6 +5,14 @@ namespace HandyControl.Controls;
 
 public class TitleElement
 {
+    public static readonly AttachedProperty<IBrush?> BorderBrushProperty =
+        AvaloniaProperty.RegisterAttached<TitleElement, AvaloniaObject, IBrush?>("BorderBrush", inherits: true);
+
+    public static void SetBorderBrush(AvaloniaObject element, IBrush? value) =>
+        element.SetValue(BorderBrushProperty, value);
+
+    public static IBrush? GetBorderBrush(AvaloniaObject element) => element.GetValue(BorderBrushProperty);
+
     public static readonly AttachedProperty<IBrush?> BackgroundProperty =
         AvaloniaProperty.RegisterAttached<TitleElement, AvaloniaObject, IBrush?>("Background", inherits: true);
 

src/Avalonia/HandyControl_Avalonia/Themes/Styles/TabControl.axaml

@@ -1,6 +1,74 @@
 <ResourceDictionary xmlns="https://github.com/avaloniaui"
-                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-    <ControlTheme x:Key="{x:Type TabControl}"
+                    xmlns:hc="clr-namespace:HandyControl.Controls"
+                    xmlns:tools="clr-namespace:HandyControl.Tools"
+                    xmlns:system="clr-namespace:System;assembly=System.Runtime">
+    <ControlTheme x:Key="TabItemStyle"
+                  TargetType="TabItem">
+        <Setter Property="Foreground"
+                Value="{DynamicResource PrimaryTextBrush}" />
+        <Setter Property="Background"
+                Value="{DynamicResource RegionBrush}" />
+        <Setter Property="BorderBrush"
+                Value="{DynamicResource TitleBrush}" />
+        <Setter Property="Margin"
+                Value="0" />
+        <Setter Property="Padding"
+                Value="{StaticResource DefaultControlPadding}" />
+        <Setter Property="MinHeight"
+                Value="{StaticResource DefaultControlHeight}" />
+        <Setter Property="HorizontalContentAlignment"
+                Value="Center" />
+        <Setter Property="VerticalContentAlignment"
+                Value="Center" />
+        <Setter Property="Template">
+            <ControlTemplate>
+                <Panel>
+                    <Border Name="mainBorder"
+                            BorderBrush="{TemplateBinding BorderBrush}"
+                            BorderThickness="0"
+                            Background="{TemplateBinding Background}"
+                            Margin="0" />
+                    <ContentPresenter Name="PART_ContentPresenter"
+                                      Padding="{TemplateBinding Padding}"
+                                      HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
+                                      VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
+                                      Content="{TemplateBinding Header}"
+                                      ContentTemplate="{TemplateBinding HeaderTemplate}"
+                                      CornerRadius="{TemplateBinding CornerRadius}"
+                                      RecognizesAccessKey="True" />
+                </Panel>
+            </ControlTemplate>
+        </Setter>
+
+        <Style Selector="^:disabled">
+            <Setter Property="Opacity"
+                    Value="0.4" />
+        </Style>
+
+        <Style Selector="^:selected">
+            <Setter Property="Foreground"
+                    Value="{DynamicResource PrimaryBrush}" />
+            <Style Selector="^[TabStripPlacement=Left] /template/ Border#mainBorder">
+                <Setter Property="BorderThickness"
+                        Value="0,0,2,0" />
+            </Style>
+            <Style Selector="^[TabStripPlacement=Top] /template/ Border#mainBorder">
+                <Setter Property="BorderThickness"
+                        Value="0,0,0,2" />
+            </Style>
+            <Style Selector="^[TabStripPlacement=Right] /template/ Border#mainBorder">
+                <Setter Property="BorderThickness"
+                        Value="2,0,0,0" />
+            </Style>
+            <Style Selector="^[TabStripPlacement=Bottom] /template/ Border#mainBorder">
+                <Setter Property="BorderThickness"
+                        Value="0,2,0,0" />
+            </Style>
+        </Style>
+    </ControlTheme>
+
+    <ControlTheme x:Key="TabControlBaseStyle"
                   TargetType="TabControl">
         <Setter Property="BorderBrush"
                 Value="{DynamicResource BorderBrush}" />
@@ -8,6 +76,8 @@
                 Value="{DynamicResource RegionBrush}" />
         <Setter Property="BorderThickness"
                 Value="1" />
+        <Setter Property="ItemContainerTheme"
+                Value="{StaticResource TabItemStyle}" />
         <Setter Property="Template">
             <ControlTemplate>
                 <DockPanel>
@@ -46,29 +116,290 @@
                     Value="Left" />
         </Style>
 
-        <Style Selector="^[TabStripPlacement=Left] /template/ ItemsPresenter#PART_ItemsPresenter > WrapPanel">
-            <Setter Property="Orientation"
-                    Value="Vertical" />
-        </Style>
-
         <Style Selector="^[TabStripPlacement=Right] /template/ ItemsPresenter#PART_ItemsPresenter">
             <Setter Property="DockPanel.Dock"
                     Value="Right" />
         </Style>
 
+        <Style Selector="^[TabStripPlacement=Left] /template/ ItemsPresenter#PART_ItemsPresenter > WrapPanel">
+            <Setter Property="Orientation"
+                    Value="Vertical" />
+        </Style>
+
         <Style Selector="^[TabStripPlacement=Right] /template/ ItemsPresenter#PART_ItemsPresenter > WrapPanel">
             <Setter Property="Orientation"
                     Value="Vertical" />
         </Style>
+    </ControlTheme>
 
-        <Style Selector="^.inline">
+    <ControlTheme x:Key="{x:Type TabControl}"
+                  BasedOn="{StaticResource TabControlBaseStyle}"
+                  TargetType="TabControl" />
+
+    <ControlTheme x:Key="TabItemInLine"
+                  BasedOn="{StaticResource TabItemStyle}"
+                  TargetType="TabItem">
+        <Setter Property="MinWidth"
+                Value="0" />
+    </ControlTheme>
+
+    <ControlTheme x:Key="TabControlInLine"
+                  BasedOn="{StaticResource TabControlBaseStyle}"
+                  TargetType="TabControl">
+        <Setter Property="ItemContainerTheme"
+                Value="{StaticResource TabItemInLine}" />
+
+        <Style Selector="^[TabStripPlacement=Left], ^[TabStripPlacement=Right]">
             <Setter Property="ItemsPanel">
                 <Setter.Value>
                     <ItemsPanelTemplate>
-                        <UniformGrid Rows="1"/>
+                        <UniformGrid Rows="0"
+                                     Columns="1" />
+                    </ItemsPanelTemplate>
+                </Setter.Value>
+            </Setter>
+        </Style>
+
+        <Style Selector="^[TabStripPlacement=Top], ^[TabStripPlacement=Bottom]">
+            <Setter Property="ItemsPanel">
+                <Setter.Value>
+                    <ItemsPanelTemplate>
+                        <UniformGrid Rows="1"
+                                     Columns="0" />
                     </ItemsPanelTemplate>
                 </Setter.Value>
             </Setter>
         </Style>
     </ControlTheme>
+
+    <ControlTheme x:Key="TabItemCapsuleBaseStyle"
+                  TargetType="TabItem">
+        <Setter Property="Background"
+                Value="{DynamicResource RegionBrush}" />
+        <Setter Property="BorderBrush"
+                Value="{DynamicResource BorderBrush}" />
+        <Setter Property="Foreground"
+                Value="{DynamicResource PrimaryTextBrush}" />
+        <Setter Property="BorderThickness"
+                Value="1" />
+        <Setter Property="VerticalAlignment"
+                Value="Center" />
+        <Setter Property="VerticalContentAlignment"
+                Value="Center" />
+        <Setter Property="HorizontalContentAlignment"
+                Value="Center" />
+        <Setter Property="hc:BorderElement.CornerRadius"
+                Value="0" />
+        <Setter Property="CornerRadius"
+                Value="{Binding $self.(hc:BorderElement.CornerRadius)}" />
+        <Setter Property="MinHeight"
+                Value="{StaticResource DefaultControlHeight}" />
+        <Setter Property="Padding"
+                Value="10,0" />
+        <Setter Property="Margin"
+                Value="-1,0,0,0" />
+        <Setter Property="Template">
+            <ControlTemplate>
+                <Border x:Name="rootBorder"
+                        CornerRadius="{TemplateBinding CornerRadius}"
+                        Background="{TemplateBinding Background}"
+                        BorderThickness="{TemplateBinding BorderThickness}"
+                        BorderBrush="{TemplateBinding BorderBrush}">
+                    <ContentPresenter Name="PART_ContentPresenter"
+                                      Padding="{TemplateBinding Padding}"
+                                      HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
+                                      VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
+                                      Content="{TemplateBinding Header}"
+                                      ContentTemplate="{TemplateBinding HeaderTemplate}"
+                                      CornerRadius="{TemplateBinding CornerRadius}"
+                                      RecognizesAccessKey="True" />
+                </Border>
+            </ControlTemplate>
+        </Setter>
+
+        <Style Selector="^:disabled">
+            <Setter Property="Opacity"
+                    Value="0.4" />
+        </Style>
+
+        <Style Selector="^:pointerover">
+            <Setter Property="Background"
+                    Value="{DynamicResource SecondaryRegionBrush}" />
+            <Setter Property="Foreground"
+                    Value="{DynamicResource PrimaryBrush}" />
+        </Style>
+
+        <Style Selector="^:selected">
+            <Setter Property="Background"
+                    Value="{Binding $self.(hc:TitleElement.Background)}" />
+            <Setter Property="Foreground"
+                    Value="{Binding $self.(hc:TitleElement.Foreground)}" />
+            <Setter Property="BorderBrush"
+                    Value="{Binding $self.(hc:TitleElement.BorderBrush)}" />
+            <Setter Property="ZIndex"
+                    Value="{x:Static system:Int32.MaxValue}" />
+        </Style>
+
+        <Style Selector="^[TabStripPlacement=Left], ^[TabStripPlacement=Right]">
+            <Setter Property="Margin"
+                    Value="0,-1,0,0" />
+        </Style>
+        <Style Selector="^[TabStripPlacement=Top], ^[TabStripPlacement=Bottom]">
+            <Setter Property="Margin"
+                    Value="-1,0,0,0" />
+        </Style>
+    </ControlTheme>
+
+    <ControlTheme x:Key="TabItemCapsuleDefault"
+                  BasedOn="{StaticResource TabItemCapsuleBaseStyle}"
+                  TargetType="TabItem" />
+
+    <ControlTheme x:Key="TabItemCapsuleHorizontalFirst"
+                  BasedOn="{StaticResource TabItemCapsuleBaseStyle}"
+                  TargetType="TabItem">
+        <Setter Property="hc:BorderElement.CornerRadius"
+                Value="4,0,0,4" />
+        <Setter Property="Margin"
+                Value="0" />
+    </ControlTheme>
+
+    <ControlTheme x:Key="TabItemCapsuleHorizontalLast"
+                  BasedOn="{StaticResource TabItemCapsuleBaseStyle}"
+                  TargetType="TabItem">
+        <Setter Property="hc:BorderElement.CornerRadius"
+                Value="0,4,4,0" />
+    </ControlTheme>
+
+    <ControlTheme x:Key="TabItemCapsuleSingle"
+                  BasedOn="{StaticResource TabItemCapsuleBaseStyle}"
+                  TargetType="TabItem">
+        <Setter Property="hc:BorderElement.CornerRadius"
+                Value="{StaticResource DefaultCornerRadius}" />
+    </ControlTheme>
+
+    <ControlTheme x:Key="TabItemCapsuleVerticalFirst"
+                  BasedOn="{StaticResource TabItemCapsuleBaseStyle}"
+                  TargetType="TabItem">
+        <Setter Property="hc:BorderElement.CornerRadius"
+                Value="4,4,0,0" />
+        <Setter Property="Margin"
+                Value="0" />
+    </ControlTheme>
+
+    <ControlTheme x:Key="TabItemCapsuleVerticalLast"
+                  BasedOn="{StaticResource TabItemCapsuleBaseStyle}"
+                  TargetType="TabItem">
+        <Setter Property="hc:BorderElement.CornerRadius"
+                Value="0,0,4,4" />
+    </ControlTheme>
+
+    <ControlTheme x:Key="TabControlCapsule"
+                  TargetType="TabControl">
+        <Setter Property="BorderThickness"
+                Value="1" />
+        <Setter Property="Background"
+                Value="{DynamicResource RegionBrush}" />
+        <Setter Property="BorderBrush"
+                Value="{DynamicResource BorderBrush}" />
+        <Setter Property="hc:TitleElement.BorderBrush"
+                Value="{DynamicResource PrimaryBrush}" />
+        <Setter Property="hc:TitleElement.Background"
+                Value="{DynamicResource RegionBrush}" />
+        <Setter Property="hc:TitleElement.Foreground"
+                Value="{DynamicResource PrimaryBrush}" />
+        <Setter Property="hc:ItemsControlAttach.ItemsContainerThemeSelector">
+            <Setter.Value>
+                <tools:TabItemCapsuleThemeSelector />
+            </Setter.Value>
+        </Setter>
+        <Setter Property="Template">
+            <ControlTemplate>
+                <DockPanel>
+                    <ItemsPresenter Name="PART_ItemsPresenter"
+                                    ItemsPanel="{TemplateBinding ItemsPanel}" />
+                    <Border Padding="{TemplateBinding Padding}"
+                            Margin="0,6,0,0"
+                            HorizontalAlignment="{TemplateBinding HorizontalAlignment}"
+                            VerticalAlignment="{TemplateBinding VerticalAlignment}"
+                            Background="{TemplateBinding Background}"
+                            BorderBrush="{TemplateBinding BorderBrush}"
+                            BorderThickness="{TemplateBinding BorderThickness}"
+                            CornerRadius="{TemplateBinding CornerRadius}">
+                        <ContentPresenter Name="PART_SelectedContentHost"
+                                          Margin="{TemplateBinding Padding}"
+                                          HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
+                                          VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
+                                          Content="{TemplateBinding SelectedContent}"
+                                          ContentTemplate="{TemplateBinding SelectedContentTemplate}" />
+                    </Border>
+                </DockPanel>
+            </ControlTemplate>
+        </Setter>
+
+        <Style Selector="^[TabStripPlacement=Top] /template/ ItemsPresenter#PART_ItemsPresenter">
+            <Setter Property="DockPanel.Dock"
+                    Value="Top" />
+            <Setter Property="Margin"
+                    Value="0,0,0,6" />
+        </Style>
+
+        <Style Selector="^[TabStripPlacement=Bottom] /template/ ItemsPresenter#PART_ItemsPresenter">
+            <Setter Property="DockPanel.Dock"
+                    Value="Bottom" />
+            <Setter Property="Margin"
+                    Value="0,6,0,0" />
+        </Style>
+
+        <Style Selector="^[TabStripPlacement=Left] /template/ ItemsPresenter#PART_ItemsPresenter">
+            <Setter Property="DockPanel.Dock"
+                    Value="Left" />
+            <Setter Property="Margin"
+                    Value="0,0,6,0" />
+        </Style>
+
+        <Style Selector="^[TabStripPlacement=Right] /template/ ItemsPresenter#PART_ItemsPresenter">
+            <Setter Property="DockPanel.Dock"
+                    Value="Right" />
+            <Setter Property="Margin"
+                    Value="6,0,0,0" />
+        </Style>
+
+        <Style Selector="^[TabStripPlacement=Left], ^[TabStripPlacement=Right]">
+            <Setter Property="ItemsPanel">
+                <Setter.Value>
+                    <ItemsPanelTemplate>
+                        <UniformGrid Rows="0"
+                                     Columns="1"
+                                     HorizontalAlignment="Center"
+                                     VerticalAlignment="Center" />
+                    </ItemsPanelTemplate>
+                </Setter.Value>
+            </Setter>
+        </Style>
+
+        <Style Selector="^[TabStripPlacement=Top], ^[TabStripPlacement=Bottom]">
+            <Setter Property="ItemsPanel">
+                <Setter.Value>
+                    <ItemsPanelTemplate>
+                        <UniformGrid Rows="1"
+                                     Columns="0"
+                                     HorizontalAlignment="Center"
+                                     VerticalAlignment="Center" />
+                    </ItemsPanelTemplate>
+                </Setter.Value>
+            </Setter>
+        </Style>
+    </ControlTheme>
+
+    <ControlTheme x:Key="TabControlCapsuleSolid"
+                  BasedOn="{StaticResource TabControlCapsule}"
+                  TargetType="TabControl">
+        <Setter Property="hc:TitleElement.BorderBrush"
+                Value="{DynamicResource TitleBrush}" />
+        <Setter Property="hc:TitleElement.Background"
+                Value="{DynamicResource TitleBrush}" />
+        <Setter Property="hc:TitleElement.Foreground"
+                Value="{DynamicResource TextIconBrush}" />
+    </ControlTheme>
+
 </ResourceDictionary>

src/Avalonia/HandyControl_Avalonia/Themes/Styles/TabItem.axaml

@@ -1,56 +0,0 @@
-<ResourceDictionary xmlns="https://github.com/avaloniaui"
-                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
-    <ControlTheme x:Key="{x:Type TabItem}"
-                  TargetType="TabItem">
-        <Setter Property="Foreground"
-                Value="{DynamicResource PrimaryTextBrush}" />
-        <Setter Property="Background"
-                Value="{DynamicResource RegionBrush}" />
-        <Setter Property="BorderBrush"
-                Value="{DynamicResource TitleBrush}" />
-        <Setter Property="Margin"
-                Value="0" />
-        <Setter Property="Padding"
-                Value="{StaticResource DefaultControlPadding}" />
-        <Setter Property="MinHeight"
-                Value="{StaticResource DefaultControlHeight}" />
-        <Setter Property="HorizontalContentAlignment"
-                Value="Center" />
-        <Setter Property="VerticalContentAlignment"
-                Value="Center" />
-        <Setter Property="Template">
-            <ControlTemplate>
-                <Panel>
-                    <Border Name="mainBorder"
-                            BorderBrush="{TemplateBinding BorderBrush}"
-                            BorderThickness="0"
-                            Background="{TemplateBinding Background}"
-                            Margin="0" />
-                    <ContentPresenter Name="PART_ContentPresenter"
-                                      Padding="{TemplateBinding Padding}"
-                                      HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
-                                      VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
-                                      Content="{TemplateBinding Header}"
-                                      ContentTemplate="{TemplateBinding HeaderTemplate}"
-                                      CornerRadius="{TemplateBinding CornerRadius}"
-                                      RecognizesAccessKey="True" />
-                </Panel>
-            </ControlTemplate>
-        </Setter>
-
-        <Style Selector="^:disabled">
-            <Setter Property="Opacity"
-                    Value="0.4" />
-        </Style>
-
-        <Style Selector="^:selected">
-            <Setter Property="Foreground"
-                    Value="{DynamicResource PrimaryBrush}" />
-
-            <Style Selector="^ /template/ Border#mainBorder">
-                <Setter Property="BorderThickness"
-                        Value="0,0,0,2" />
-            </Style>
-        </Style>
-    </ControlTheme>
-</ResourceDictionary>

src/Avalonia/HandyControl_Avalonia/Themes/Theme.axaml

@@ -26,7 +26,6 @@
                 <MergeResourceInclude Source="/Themes/Styles/CheckBox.axaml" />
                 <MergeResourceInclude Source="/Themes/Styles/Border.axaml" />
                 <MergeResourceInclude Source="/Themes/Styles/ItemsControl.axaml" />
-                <MergeResourceInclude Source="/Themes/Styles/TabItem.axaml" />
                 <MergeResourceInclude Source="/Themes/Styles/TabControl.axaml" />
                 <MergeResourceInclude Source="/Themes/Styles/ScrollViewer.axaml" />
                 <MergeResourceInclude Source="/Themes/Styles/ListBox.axaml" />

src/Avalonia/HandyControl_Avalonia/Tools/StyleSelector/TabItemCapsuleStyleSelector.cs

@@ -0,0 +1,35 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Styling;
+using HandyControl.Data;
+
+namespace HandyControl.Tools;
+
+public class TabItemCapsuleThemeSelector : ThemeSelector
+{
+    public override ControlTheme? SelectTheme(object? item, AvaloniaObject? container)
+    {
+        if (container is not TabItem { Parent: TabControl tabControl } tabItem)
+        {
+            return null;
+        }
+
+        int count = tabControl.Items.Count;
+        if (count == 1)
+        {
+            return ResourceHelper.GetResource<ControlTheme>(ResourceToken.TabItemCapsuleSingle);
+        }
+
+        int index = tabControl.IndexFromContainer(tabItem);
+        return index == 0
+            ? ResourceHelper.GetResource<ControlTheme>(
+                tabControl.TabStripPlacement is Dock.Top or Dock.Bottom
+                    ? ResourceToken.TabItemCapsuleHorizontalFirst
+                    : ResourceToken.TabItemCapsuleVerticalFirst)
+            : ResourceHelper.GetResource<ControlTheme>(index == count - 1
+                ? tabControl.TabStripPlacement is Dock.Top or Dock.Bottom
+                    ? ResourceToken.TabItemCapsuleHorizontalLast
+                    : ResourceToken.TabItemCapsuleVerticalLast
+                : ResourceToken.TabItemCapsuleDefault);
+    }
+}

src/Avalonia/HandyControl_Avalonia/Tools/StyleSelector/ThemeSelector.cs

@@ -0,0 +1,9 @@
+using Avalonia;
+using Avalonia.Styling;
+
+namespace HandyControl.Tools;
+
+public class ThemeSelector
+{
+    public virtual ControlTheme? SelectTheme(object? item, AvaloniaObject? container) => null;
+}

src/Shared/HandyControl_Shared/Themes/Styles/TabControl.xaml

@@ -189,6 +189,7 @@
     <Style x:Key="TabControlCapsule" TargetType="TabControl">
         <Setter Property="BorderThickness" Value="1" />
         <Setter Property="Background" Value="{DynamicResource RegionBrush}" />
+        <Setter Property="BorderBrush" Value="{DynamicResource BorderBrush}" />
         <Setter Property="hc:TitleElement.BorderBrush" Value="{DynamicResource PrimaryBrush}" />
         <Setter Property="hc:TitleElement.Background" Value="{DynamicResource RegionBrush}" />
         <Setter Property="hc:TitleElement.Foreground" Value="{DynamicResource PrimaryBrush}" />
@@ -210,7 +211,7 @@
                             <RowDefinition x:Name="RowDefinition1" Height="*" />
                         </Grid.RowDefinitions>
                         <UniformGrid Rows="1" KeyboardNavigation.TabNavigation="Once" KeyboardNavigation.DirectionalNavigation="Cycle" HorizontalAlignment="Center" VerticalAlignment="Center" x:Name="headerPanel" Background="Transparent" Grid.Column="0" IsItemsHost="true" Margin="0" Grid.Row="0"/>
-                        <Border x:Name="contentPanel" Margin="0,6,0,0" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" BorderThickness="{TemplateBinding BorderThickness}" BorderBrush="{DynamicResource BorderBrush}" Background="{TemplateBinding Background}" Grid.Column="0" Grid.Row="1">
+                        <Border x:Name="contentPanel" Margin="0,6,0,0" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" BorderThickness="{TemplateBinding BorderThickness}" BorderBrush="{TemplateBinding BorderBrush}" Background="{TemplateBinding Background}" Grid.Column="0" Grid.Row="1">
                             <ContentPresenter x:Name="PART_SelectedContentHost" ContentSource="SelectedContent" Margin="0" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
                         </Border>
                     </Grid>

src/Shared/HandyControl_Shared/Tools/StyleSelector/TabItemCapsuleStyleSelector.cs

@@ -8,27 +8,28 @@ public class TabItemCapsuleStyleSelector : StyleSelector
 {
     public override Style SelectStyle(object item, DependencyObject container)
     {
-        if (container is TabItem tabItem && VisualHelper.GetParent<TabControl>(tabItem) is { } tabControl)
+        if (container is not TabItem tabItem || VisualHelper.GetParent<TabControl>(tabItem) is not { } tabControl)
         {
-            var count = tabControl.Items.Count;
+            return null;
-            if (count == 1)
-            {
-                return ResourceHelper.GetResourceInternal<Style>(ResourceToken.TabItemCapsuleSingle);
-            }
-
-            var index = tabControl.ItemContainerGenerator.IndexFromContainer(tabItem);
-            return index == 0
-                ? ResourceHelper.GetResourceInternal<Style>(
-                    tabControl.TabStripPlacement == Dock.Top || tabControl.TabStripPlacement == Dock.Bottom
-                        ? ResourceToken.TabItemCapsuleHorizontalFirst
-                        : ResourceToken.TabItemCapsuleVerticalFirst)
-                : ResourceHelper.GetResourceInternal<Style>(index == count - 1
-                    ? tabControl.TabStripPlacement == Dock.Top || tabControl.TabStripPlacement == Dock.Bottom
-                        ? ResourceToken.TabItemCapsuleHorizontalLast
-                        : ResourceToken.TabItemCapsuleVerticalLast
-                    : ResourceToken.TabItemCapsuleDefault);
         }
 
-        return null;
+        var count = tabControl.Items.Count;
+        if (count == 1)
+        {
+            return ResourceHelper.GetResourceInternal<Style>(ResourceToken.TabItemCapsuleSingle);
+        }
+
+        var index = tabControl.ItemContainerGenerator.IndexFromContainer(tabItem);
+        return index == 0
+            ? ResourceHelper.GetResourceInternal<Style>(
+                tabControl.TabStripPlacement is Dock.Top or Dock.Bottom
+                    ? ResourceToken.TabItemCapsuleHorizontalFirst
+                    : ResourceToken.TabItemCapsuleVerticalFirst)
+            : ResourceHelper.GetResourceInternal<Style>(index == count - 1
+                ? tabControl.TabStripPlacement is Dock.Top or Dock.Bottom
+                    ? ResourceToken.TabItemCapsuleHorizontalLast
+                    : ResourceToken.TabItemCapsuleVerticalLast
+                : ResourceToken.TabItemCapsuleDefault);
+
     }
 }