From 2d70c979f1071e5792ab8e3d89b9e80b1e22e01f Mon Sep 17 00:00:00 2001
From: Sebastian Klatte <sebastian.klatte@qonlab.com>
Date: Sat, 28 Mar 2026 22:42:08 +0100
Subject: [PATCH 1/5] Add expander functionality to define custom header
 height.

---
 .../Pages/ExpandersDemo.axaml                 |  2 ++
 Material.Styles/Assists/ExpanderAssist.cs.cs  | 16 ++++++++++++++
 .../Converters/BottomMarginConverter.cs       | 17 ++++++++++++++
 .../Converters/LeftMarginConverter.cs         | 17 ++++++++++++++
 .../Converters/RightMarginConverter.cs        | 17 ++++++++++++++
 .../Converters/TopMarginConverter.cs          | 17 ++++++++++++++
 .../Resources/Themes/Expander.axaml           | 22 ++++++++++++++-----
 7 files changed, 102 insertions(+), 6 deletions(-)
 create mode 100644 Material.Styles/Assists/ExpanderAssist.cs.cs
 create mode 100644 Material.Styles/Converters/BottomMarginConverter.cs
 create mode 100644 Material.Styles/Converters/LeftMarginConverter.cs
 create mode 100644 Material.Styles/Converters/RightMarginConverter.cs
 create mode 100644 Material.Styles/Converters/TopMarginConverter.cs

diff --git a/Material.Avalonia.Demo/Pages/ExpandersDemo.axaml b/Material.Avalonia.Demo/Pages/ExpandersDemo.axaml
index e090c677..2216dffb 100644
--- a/Material.Avalonia.Demo/Pages/ExpandersDemo.axaml
+++ b/Material.Avalonia.Demo/Pages/ExpandersDemo.axaml
@@ -2,6 +2,7 @@
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             xmlns:assists="clr-namespace:Material.Styles.Assists;assembly=Material.Styles"
              xmlns:viewModels="clr-namespace:Material.Avalonia.Demo.ViewModels"
              mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
              x:Class="Material.Avalonia.Demo.Pages.ExpandersDemo"
@@ -34,6 +35,7 @@
         
         <Expander Header="This expander inflates content from upside!"
                   ExpandDirection="Up"
+                  assists:ExpanderAssist.HeaderHeight="64"
                   Content="{Binding }"
                   ContentTemplate="{StaticResource LoremContentTemplate}"/>
         
diff --git a/Material.Styles/Assists/ExpanderAssist.cs.cs b/Material.Styles/Assists/ExpanderAssist.cs.cs
new file mode 100644
index 00000000..49e907f6
--- /dev/null
+++ b/Material.Styles/Assists/ExpanderAssist.cs.cs
@@ -0,0 +1,16 @@
+using Avalonia;
+using Avalonia.Controls;
+
+namespace Material.Styles.Assists;
+
+public static class ExpanderAssist {
+    public static readonly AttachedProperty<double> HeaderHeightProperty =
+        AvaloniaProperty.RegisterAttached<Expander, double>(
+            "HeaderHeight", typeof(Expander), 48);
+
+    public static void SetHeaderHeight(AvaloniaObject element, double value) =>
+        element.SetValue(HeaderHeightProperty, value);
+
+    public static double GetHeaderHeight(AvaloniaObject element) =>
+        element.GetValue(HeaderHeightProperty);
+}
\ No newline at end of file
diff --git a/Material.Styles/Converters/BottomMarginConverter.cs b/Material.Styles/Converters/BottomMarginConverter.cs
new file mode 100644
index 00000000..ff5abc6a
--- /dev/null
+++ b/Material.Styles/Converters/BottomMarginConverter.cs
@@ -0,0 +1,17 @@
+using System;
+using System.Globalization;
+using Avalonia;
+using Avalonia.Data;
+using Avalonia.Data.Converters;
+
+namespace Material.Styles.Converters;
+
+public class BottomMarginConverter : IValueConverter {
+    public object Convert(object value, Type targetType, object parameter, CultureInfo culture) {
+        double bottom = value is double d ? d : 0;
+        return new Thickness(0, 0, 0, bottom);
+    }
+
+    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        => BindingOperations.DoNothing;
+}
\ No newline at end of file
diff --git a/Material.Styles/Converters/LeftMarginConverter.cs b/Material.Styles/Converters/LeftMarginConverter.cs
new file mode 100644
index 00000000..587bc94e
--- /dev/null
+++ b/Material.Styles/Converters/LeftMarginConverter.cs
@@ -0,0 +1,17 @@
+using System;
+using System.Globalization;
+using Avalonia;
+using Avalonia.Data;
+using Avalonia.Data.Converters;
+
+namespace Material.Styles.Converters;
+
+public class LeftMarginConverter : IValueConverter {
+    public object Convert(object value, Type targetType, object parameter, CultureInfo culture) {
+        double left = value is double d ? d : 0;
+        return new Thickness(left, 0, 0, 0);
+    }
+
+    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        => BindingOperations.DoNothing;
+}
\ No newline at end of file
diff --git a/Material.Styles/Converters/RightMarginConverter.cs b/Material.Styles/Converters/RightMarginConverter.cs
new file mode 100644
index 00000000..703c0adf
--- /dev/null
+++ b/Material.Styles/Converters/RightMarginConverter.cs
@@ -0,0 +1,17 @@
+using System;
+using System.Globalization;
+using Avalonia;
+using Avalonia.Data;
+using Avalonia.Data.Converters;
+
+namespace Material.Styles.Converters;
+
+public class RightMarginConverter : IValueConverter {
+    public object Convert(object value, Type targetType, object parameter, CultureInfo culture) {
+        double right = value is double d ? d : 0;
+        return new Thickness(0, 0, right, 0);
+    }
+
+    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        => BindingOperations.DoNothing;
+}
\ No newline at end of file
diff --git a/Material.Styles/Converters/TopMarginConverter.cs b/Material.Styles/Converters/TopMarginConverter.cs
new file mode 100644
index 00000000..b882e7b9
--- /dev/null
+++ b/Material.Styles/Converters/TopMarginConverter.cs
@@ -0,0 +1,17 @@
+using System;
+using System.Globalization;
+using Avalonia;
+using Avalonia.Data;
+using Avalonia.Data.Converters;
+
+namespace Material.Styles.Converters;
+
+public class TopMarginConverter : IValueConverter {
+    public object Convert(object value, Type targetType, object parameter, CultureInfo culture) {
+        double top = value is double d ? d : 0;
+        return new Thickness(0, top, 0, 0);
+    }
+
+    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        => BindingOperations.DoNothing;
+}
\ No newline at end of file
diff --git a/Material.Styles/Resources/Themes/Expander.axaml b/Material.Styles/Resources/Themes/Expander.axaml
index 81641fa7..3cfe0383 100644
--- a/Material.Styles/Resources/Themes/Expander.axaml
+++ b/Material.Styles/Resources/Themes/Expander.axaml
@@ -1,12 +1,18 @@
 <ResourceDictionary xmlns="https://github.com/avaloniaui"
                     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                     xmlns:assists="clr-namespace:Material.Styles.Assists"
-                    xmlns:controls="clr-namespace:Material.Styles.Controls">
+                    xmlns:controls="clr-namespace:Material.Styles.Controls"
+                    xmlns:converters="clr-namespace:Material.Styles.Converters">
+  <converters:BottomMarginConverter x:Key="BottomMarginConverter" />
+  <converters:TopMarginConverter x:Key="TopMarginConverter" />
+  <converters:LeftMarginConverter x:Key="LeftMarginConverter" />
+  <converters:RightMarginConverter x:Key="RightMarginConverter" />
+
   <ControlTheme x:Key="ExpanderToggleButtonPart" TargetType="ToggleButton">
     <Setter Property="Background" Value="Transparent" />
     <Setter Property="ClipToBounds" Value="False" />
     <Setter Property="FocusAdorner" Value="{x:Null}"></Setter>
-    <Setter Property="Height" Value="48" />
+    <Setter Property="Height" Value="{TemplateBinding assists:ExpanderAssist.HeaderHeight}" />
     <Setter Property="assists:ToggleButtonAssist.UncheckedBackground" Value="Transparent" />
     <Setter Property="HorizontalAlignment" Value="Stretch"/>
     <Setter Property="HorizontalContentAlignment" Value="Stretch" />
@@ -180,7 +186,8 @@
       <Style Selector="^ /template/ controls|ContentExpandControl#PART_ContentExpand">
         <Setter Property="Orientation" Value="Vertical" />
         <Setter Property="VerticalAlignment" Value="Bottom" />
-        <Setter Property="Margin" Value="0,0,0,48" />
+        <Setter Property="Margin" Value="{TemplateBinding assists:ExpanderAssist.HeaderHeight, 
+                                                          Converter={StaticResource BottomMarginConverter}}" />
       </Style>
 
       <Style Selector="^ /template/ LayoutTransformControl#PART_ToggleTransform">
@@ -196,7 +203,8 @@
       <Style Selector="^ /template/ controls|ContentExpandControl#PART_ContentExpand">
         <Setter Property="Orientation" Value="Vertical" />
         <Setter Property="VerticalAlignment" Value="Top" />
-        <Setter Property="Margin" Value="0,48,0,0" />
+        <Setter Property="Margin" Value="{TemplateBinding assists:ExpanderAssist.HeaderHeight, 
+                                                          Converter={StaticResource TopMarginConverter}}" />
       </Style>
 
       <Style Selector="^ /template/ LayoutTransformControl#PART_ToggleTransform">
@@ -212,7 +220,8 @@
       <Style Selector="^ /template/ controls|ContentExpandControl#PART_ContentExpand">
         <Setter Property="Orientation" Value="Horizontal" />
         <Setter Property="HorizontalAlignment" Value="Right" />
-        <Setter Property="Margin" Value="0,0,48,0" />
+        <Setter Property="Margin" Value="{TemplateBinding assists:ExpanderAssist.HeaderHeight, 
+                                                          Converter={StaticResource RightMarginConverter}}" />
       </Style>
 
       <Style Selector="^ /template/ LayoutTransformControl#PART_ToggleTransform">
@@ -229,7 +238,8 @@
       <Style Selector="^ /template/ controls|ContentExpandControl#PART_ContentExpand">
         <Setter Property="Orientation" Value="Horizontal" />
         <Setter Property="HorizontalAlignment" Value="Left" />
-        <Setter Property="Margin" Value="48,0,0,0" />
+        <Setter Property="Margin" Value="{TemplateBinding assists:ExpanderAssist.HeaderHeight, 
+                                                          Converter={StaticResource LeftMarginConverter}}" />
       </Style>
 
       <Style Selector="^ /template/ LayoutTransformControl#PART_ToggleTransform">

From 6c91ae584fc6dcca47a9d8151b4163dd8e29a9dd Mon Sep 17 00:00:00 2001
From: Sebastian Klatte <sebastian.klatte@qonlab.com>
Date: Sat, 28 Mar 2026 22:48:39 +0100
Subject: [PATCH 2/5] Improve with MarginSideConverter.

---
 .../Converters/BottomMarginConverter.cs       | 17 -------------
 .../Converters/LeftMarginConverter.cs         | 17 -------------
 .../Converters/MarginSideConverter.cs         | 25 +++++++++++++++++++
 .../Converters/RightMarginConverter.cs        | 17 -------------
 .../Converters/TopMarginConverter.cs          | 17 -------------
 .../Resources/Themes/Expander.axaml           | 17 +++++++------
 6 files changed, 34 insertions(+), 76 deletions(-)
 delete mode 100644 Material.Styles/Converters/BottomMarginConverter.cs
 delete mode 100644 Material.Styles/Converters/LeftMarginConverter.cs
 create mode 100644 Material.Styles/Converters/MarginSideConverter.cs
 delete mode 100644 Material.Styles/Converters/RightMarginConverter.cs
 delete mode 100644 Material.Styles/Converters/TopMarginConverter.cs

diff --git a/Material.Styles/Converters/BottomMarginConverter.cs b/Material.Styles/Converters/BottomMarginConverter.cs
deleted file mode 100644
index ff5abc6a..00000000
--- a/Material.Styles/Converters/BottomMarginConverter.cs
+++ /dev/null
@@ -1,17 +0,0 @@
-using System;
-using System.Globalization;
-using Avalonia;
-using Avalonia.Data;
-using Avalonia.Data.Converters;
-
-namespace Material.Styles.Converters;
-
-public class BottomMarginConverter : IValueConverter {
-    public object Convert(object value, Type targetType, object parameter, CultureInfo culture) {
-        double bottom = value is double d ? d : 0;
-        return new Thickness(0, 0, 0, bottom);
-    }
-
-    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
-        => BindingOperations.DoNothing;
-}
\ No newline at end of file
diff --git a/Material.Styles/Converters/LeftMarginConverter.cs b/Material.Styles/Converters/LeftMarginConverter.cs
deleted file mode 100644
index 587bc94e..00000000
--- a/Material.Styles/Converters/LeftMarginConverter.cs
+++ /dev/null
@@ -1,17 +0,0 @@
-using System;
-using System.Globalization;
-using Avalonia;
-using Avalonia.Data;
-using Avalonia.Data.Converters;
-
-namespace Material.Styles.Converters;
-
-public class LeftMarginConverter : IValueConverter {
-    public object Convert(object value, Type targetType, object parameter, CultureInfo culture) {
-        double left = value is double d ? d : 0;
-        return new Thickness(left, 0, 0, 0);
-    }
-
-    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
-        => BindingOperations.DoNothing;
-}
\ No newline at end of file
diff --git a/Material.Styles/Converters/MarginSideConverter.cs b/Material.Styles/Converters/MarginSideConverter.cs
new file mode 100644
index 00000000..000a3175
--- /dev/null
+++ b/Material.Styles/Converters/MarginSideConverter.cs
@@ -0,0 +1,25 @@
+using System;
+using System.Globalization;
+using Avalonia;
+using Avalonia.Data;
+using Avalonia.Data.Converters;
+
+namespace Material.Styles.Converters;
+
+public class MarginSideConverter : IValueConverter {
+    public object Convert(object value, Type targetType, object parameter, CultureInfo culture) {
+        double v = value is double d ? d : 0;
+        string? side = parameter?.ToString()?.ToLowerInvariant();
+
+        return side switch {
+            "top" => new Thickness(0, v, 0, 0),
+            "bottom" => new Thickness(0, 0, 0, v),
+            "left" => new Thickness(0, 0, v, 0),
+            "right" => new Thickness(v, 0, 0, 0),
+            _ => new Thickness(0)   // fallback
+        };
+    }
+
+    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        => BindingOperations.DoNothing;
+}
\ No newline at end of file
diff --git a/Material.Styles/Converters/RightMarginConverter.cs b/Material.Styles/Converters/RightMarginConverter.cs
deleted file mode 100644
index 703c0adf..00000000
--- a/Material.Styles/Converters/RightMarginConverter.cs
+++ /dev/null
@@ -1,17 +0,0 @@
-using System;
-using System.Globalization;
-using Avalonia;
-using Avalonia.Data;
-using Avalonia.Data.Converters;
-
-namespace Material.Styles.Converters;
-
-public class RightMarginConverter : IValueConverter {
-    public object Convert(object value, Type targetType, object parameter, CultureInfo culture) {
-        double right = value is double d ? d : 0;
-        return new Thickness(0, 0, right, 0);
-    }
-
-    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
-        => BindingOperations.DoNothing;
-}
\ No newline at end of file
diff --git a/Material.Styles/Converters/TopMarginConverter.cs b/Material.Styles/Converters/TopMarginConverter.cs
deleted file mode 100644
index b882e7b9..00000000
--- a/Material.Styles/Converters/TopMarginConverter.cs
+++ /dev/null
@@ -1,17 +0,0 @@
-using System;
-using System.Globalization;
-using Avalonia;
-using Avalonia.Data;
-using Avalonia.Data.Converters;
-
-namespace Material.Styles.Converters;
-
-public class TopMarginConverter : IValueConverter {
-    public object Convert(object value, Type targetType, object parameter, CultureInfo culture) {
-        double top = value is double d ? d : 0;
-        return new Thickness(0, top, 0, 0);
-    }
-
-    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
-        => BindingOperations.DoNothing;
-}
\ No newline at end of file
diff --git a/Material.Styles/Resources/Themes/Expander.axaml b/Material.Styles/Resources/Themes/Expander.axaml
index 3cfe0383..ace2af6b 100644
--- a/Material.Styles/Resources/Themes/Expander.axaml
+++ b/Material.Styles/Resources/Themes/Expander.axaml
@@ -3,10 +3,7 @@
                     xmlns:assists="clr-namespace:Material.Styles.Assists"
                     xmlns:controls="clr-namespace:Material.Styles.Controls"
                     xmlns:converters="clr-namespace:Material.Styles.Converters">
-  <converters:BottomMarginConverter x:Key="BottomMarginConverter" />
-  <converters:TopMarginConverter x:Key="TopMarginConverter" />
-  <converters:LeftMarginConverter x:Key="LeftMarginConverter" />
-  <converters:RightMarginConverter x:Key="RightMarginConverter" />
+  <converters:MarginSideConverter x:Key="MarginSideConverter" />
 
   <ControlTheme x:Key="ExpanderToggleButtonPart" TargetType="ToggleButton">
     <Setter Property="Background" Value="Transparent" />
@@ -187,7 +184,8 @@
         <Setter Property="Orientation" Value="Vertical" />
         <Setter Property="VerticalAlignment" Value="Bottom" />
         <Setter Property="Margin" Value="{TemplateBinding assists:ExpanderAssist.HeaderHeight, 
-                                                          Converter={StaticResource BottomMarginConverter}}" />
+                                                          Converter={StaticResource MarginSideConverter},
+                                                          ConverterParameter=Bottom}" />
       </Style>
 
       <Style Selector="^ /template/ LayoutTransformControl#PART_ToggleTransform">
@@ -204,7 +202,8 @@
         <Setter Property="Orientation" Value="Vertical" />
         <Setter Property="VerticalAlignment" Value="Top" />
         <Setter Property="Margin" Value="{TemplateBinding assists:ExpanderAssist.HeaderHeight, 
-                                                          Converter={StaticResource TopMarginConverter}}" />
+                                                          Converter={StaticResource MarginSideConverter},
+                                                          ConverterParameter=Top}" />
       </Style>
 
       <Style Selector="^ /template/ LayoutTransformControl#PART_ToggleTransform">
@@ -221,7 +220,8 @@
         <Setter Property="Orientation" Value="Horizontal" />
         <Setter Property="HorizontalAlignment" Value="Right" />
         <Setter Property="Margin" Value="{TemplateBinding assists:ExpanderAssist.HeaderHeight, 
-                                                          Converter={StaticResource RightMarginConverter}}" />
+                                                          Converter={StaticResource MarginSideConverter},
+                                                          ConverterParameter=Right}" />
       </Style>
 
       <Style Selector="^ /template/ LayoutTransformControl#PART_ToggleTransform">
@@ -239,7 +239,8 @@
         <Setter Property="Orientation" Value="Horizontal" />
         <Setter Property="HorizontalAlignment" Value="Left" />
         <Setter Property="Margin" Value="{TemplateBinding assists:ExpanderAssist.HeaderHeight, 
-                                                          Converter={StaticResource LeftMarginConverter}}" />
+                                                          Converter={StaticResource MarginSideConverter},
+                                                          ConverterParameter=Left}" />
       </Style>
 
       <Style Selector="^ /template/ LayoutTransformControl#PART_ToggleTransform">

From d5f942f9b94c9c7692e214718de71d41e2d00b2a Mon Sep 17 00:00:00 2001
From: Sebastian Klatte <sebastian.klatte@qonlab.com>
Date: Sun, 29 Mar 2026 17:20:55 +0200
Subject: [PATCH 3/5] Migrate expander to DockPanel.

---
 .../Pages/ExpandersDemo.axaml                 |  1 -
 Material.Styles/Assists/ExpanderAssist.cs.cs  | 16 ----
 .../Converters/MarginSideConverter.cs         | 25 ------
 .../Resources/Themes/Expander.axaml           | 89 ++++++++-----------
 4 files changed, 36 insertions(+), 95 deletions(-)
 delete mode 100644 Material.Styles/Assists/ExpanderAssist.cs.cs
 delete mode 100644 Material.Styles/Converters/MarginSideConverter.cs

diff --git a/Material.Avalonia.Demo/Pages/ExpandersDemo.axaml b/Material.Avalonia.Demo/Pages/ExpandersDemo.axaml
index 2216dffb..7c7fd93c 100644
--- a/Material.Avalonia.Demo/Pages/ExpandersDemo.axaml
+++ b/Material.Avalonia.Demo/Pages/ExpandersDemo.axaml
@@ -35,7 +35,6 @@
         
         <Expander Header="This expander inflates content from upside!"
                   ExpandDirection="Up"
-                  assists:ExpanderAssist.HeaderHeight="64"
                   Content="{Binding }"
                   ContentTemplate="{StaticResource LoremContentTemplate}"/>
         
diff --git a/Material.Styles/Assists/ExpanderAssist.cs.cs b/Material.Styles/Assists/ExpanderAssist.cs.cs
deleted file mode 100644
index 49e907f6..00000000
--- a/Material.Styles/Assists/ExpanderAssist.cs.cs
+++ /dev/null
@@ -1,16 +0,0 @@
-using Avalonia;
-using Avalonia.Controls;
-
-namespace Material.Styles.Assists;
-
-public static class ExpanderAssist {
-    public static readonly AttachedProperty<double> HeaderHeightProperty =
-        AvaloniaProperty.RegisterAttached<Expander, double>(
-            "HeaderHeight", typeof(Expander), 48);
-
-    public static void SetHeaderHeight(AvaloniaObject element, double value) =>
-        element.SetValue(HeaderHeightProperty, value);
-
-    public static double GetHeaderHeight(AvaloniaObject element) =>
-        element.GetValue(HeaderHeightProperty);
-}
\ No newline at end of file
diff --git a/Material.Styles/Converters/MarginSideConverter.cs b/Material.Styles/Converters/MarginSideConverter.cs
deleted file mode 100644
index 000a3175..00000000
--- a/Material.Styles/Converters/MarginSideConverter.cs
+++ /dev/null
@@ -1,25 +0,0 @@
-using System;
-using System.Globalization;
-using Avalonia;
-using Avalonia.Data;
-using Avalonia.Data.Converters;
-
-namespace Material.Styles.Converters;
-
-public class MarginSideConverter : IValueConverter {
-    public object Convert(object value, Type targetType, object parameter, CultureInfo culture) {
-        double v = value is double d ? d : 0;
-        string? side = parameter?.ToString()?.ToLowerInvariant();
-
-        return side switch {
-            "top" => new Thickness(0, v, 0, 0),
-            "bottom" => new Thickness(0, 0, 0, v),
-            "left" => new Thickness(0, 0, v, 0),
-            "right" => new Thickness(v, 0, 0, 0),
-            _ => new Thickness(0)   // fallback
-        };
-    }
-
-    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
-        => BindingOperations.DoNothing;
-}
\ No newline at end of file
diff --git a/Material.Styles/Resources/Themes/Expander.axaml b/Material.Styles/Resources/Themes/Expander.axaml
index ace2af6b..eebdc349 100644
--- a/Material.Styles/Resources/Themes/Expander.axaml
+++ b/Material.Styles/Resources/Themes/Expander.axaml
@@ -3,13 +3,12 @@
                     xmlns:assists="clr-namespace:Material.Styles.Assists"
                     xmlns:controls="clr-namespace:Material.Styles.Controls"
                     xmlns:converters="clr-namespace:Material.Styles.Converters">
-  <converters:MarginSideConverter x:Key="MarginSideConverter" />
 
   <ControlTheme x:Key="ExpanderToggleButtonPart" TargetType="ToggleButton">
     <Setter Property="Background" Value="Transparent" />
     <Setter Property="ClipToBounds" Value="False" />
-    <Setter Property="FocusAdorner" Value="{x:Null}"></Setter>
-    <Setter Property="Height" Value="{TemplateBinding assists:ExpanderAssist.HeaderHeight}" />
+    <Setter Property="FocusAdorner" Value="{x:Null}"/>
+    <Setter Property="MinHeight" Value="48" />
     <Setter Property="assists:ToggleButtonAssist.UncheckedBackground" Value="Transparent" />
     <Setter Property="HorizontalAlignment" Value="Stretch"/>
     <Setter Property="HorizontalContentAlignment" Value="Stretch" />
@@ -54,7 +53,7 @@
         </Transitions>
       </Setter>
     </Style>
-    
+
     <Style Selector="^:focus-visible">
       <Setter Property="BorderThickness" Value="2"/>
       <Setter Property="BorderBrush" Value="{DynamicResource MaterialPrimaryLightBrush}"/>
@@ -130,14 +129,10 @@
                 assists:ShadowAssist.ShadowDepth="{TemplateBinding assists:ShadowAssist.ShadowDepth}">
           <Border Name="PART_InnerBorder"
                   CornerRadius="{TemplateBinding CornerRadius}">
-            <Panel>
-              <controls:ContentExpandControl Name="PART_ContentExpand"
-                                             Content="{TemplateBinding Content}"
-                                             ContentTemplate="{TemplateBinding ContentTemplate}"
-                                             HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
-                                             VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" />
 
-              <LayoutTransformControl Name="PART_ToggleTransform">
+            <DockPanel>
+              <LayoutTransformControl Name="PART_ToggleTransform"
+                                      DockPanel.Dock="Top">
                 <ToggleButton Name="PART_ToggleButton"
                               Content="{TemplateBinding Header}"
                               ContentTemplate="{TemplateBinding HeaderTemplate}"
@@ -145,7 +140,14 @@
                               Foreground="{DynamicResource MaterialBodyBrush}"
                               IsChecked="{TemplateBinding IsExpanded, Mode=TwoWay}" />
               </LayoutTransformControl>
-            </Panel>
+
+              <controls:ContentExpandControl Name="PART_ContentExpand"
+                                             Content="{TemplateBinding Content}"
+                                             ContentTemplate="{TemplateBinding ContentTemplate}"
+                                             HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
+                                             VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" />
+            </DockPanel>
+
           </Border>
         </Border>
       </ControlTemplate>
@@ -179,75 +181,56 @@
       <Setter Property="Multiplier" Value="1" />
     </Style>
 
-    <Style Selector="^:up">
-      <Style Selector="^ /template/ controls|ContentExpandControl#PART_ContentExpand">
-        <Setter Property="Orientation" Value="Vertical" />
-        <Setter Property="VerticalAlignment" Value="Bottom" />
-        <Setter Property="Margin" Value="{TemplateBinding assists:ExpanderAssist.HeaderHeight, 
-                                                          Converter={StaticResource MarginSideConverter},
-                                                          ConverterParameter=Bottom}" />
-      </Style>
 
+    <Style Selector="^:up">
       <Style Selector="^ /template/ LayoutTransformControl#PART_ToggleTransform">
-        <Setter Property="VerticalAlignment" Value="Bottom" />
+        <Setter Property="DockPanel.Dock" Value="Bottom"/>
+      </Style>
+      <Style Selector="^ /template/ controls|ContentExpandControl#PART_ContentExpand">
+        <Setter Property="Orientation" Value="Vertical"/>
+        <Setter Property="VerticalAlignment" Value="Bottom"/>
       </Style>
-
       <Style Selector="^ /template/ ToggleButton#PART_ToggleButton">
         <Setter Property="Theme" Value="{StaticResource UpExpanderToggleButtonPart}" />
       </Style>
     </Style>
 
     <Style Selector="^:down">
-      <Style Selector="^ /template/ controls|ContentExpandControl#PART_ContentExpand">
-        <Setter Property="Orientation" Value="Vertical" />
-        <Setter Property="VerticalAlignment" Value="Top" />
-        <Setter Property="Margin" Value="{TemplateBinding assists:ExpanderAssist.HeaderHeight, 
-                                                          Converter={StaticResource MarginSideConverter},
-                                                          ConverterParameter=Top}" />
-      </Style>
-
       <Style Selector="^ /template/ LayoutTransformControl#PART_ToggleTransform">
-        <Setter Property="VerticalAlignment" Value="Top" />
+        <Setter Property="DockPanel.Dock" Value="Top"/>
+      </Style>
+      <Style Selector="^ /template/ controls|ContentExpandControl#PART_ContentExpand">
+        <Setter Property="Orientation" Value="Vertical"/>
+        <Setter Property="VerticalAlignment" Value="Top"/>
       </Style>
-
       <Style Selector="^ /template/ ToggleButton#PART_ToggleButton">
         <Setter Property="Theme" Value="{StaticResource DownExpanderToggleButtonPart}" />
       </Style>
     </Style>
 
     <Style Selector="^:left">
-      <Style Selector="^ /template/ controls|ContentExpandControl#PART_ContentExpand">
-        <Setter Property="Orientation" Value="Horizontal" />
-        <Setter Property="HorizontalAlignment" Value="Right" />
-        <Setter Property="Margin" Value="{TemplateBinding assists:ExpanderAssist.HeaderHeight, 
-                                                          Converter={StaticResource MarginSideConverter},
-                                                          ConverterParameter=Right}" />
-      </Style>
-
       <Style Selector="^ /template/ LayoutTransformControl#PART_ToggleTransform">
         <Setter Property="LayoutTransform" Value="rotate(90deg)" />
-        <Setter Property="HorizontalAlignment" Value="Right" />
+        <Setter Property="DockPanel.Dock" Value="Right"/>
+      </Style>
+      <Style Selector="^ /template/ controls|ContentExpandControl#PART_ContentExpand">
+        <Setter Property="Orientation" Value="Horizontal"/>
+        <Setter Property="HorizontalAlignment" Value="Right"/>
       </Style>
-
       <Style Selector="^ /template/ ToggleButton#PART_ToggleButton">
         <Setter Property="Theme" Value="{StaticResource LeftExpanderToggleButtonPart}" />
       </Style>
     </Style>
 
     <Style Selector="^:right">
-      <Style Selector="^ /template/ controls|ContentExpandControl#PART_ContentExpand">
-        <Setter Property="Orientation" Value="Horizontal" />
-        <Setter Property="HorizontalAlignment" Value="Left" />
-        <Setter Property="Margin" Value="{TemplateBinding assists:ExpanderAssist.HeaderHeight, 
-                                                          Converter={StaticResource MarginSideConverter},
-                                                          ConverterParameter=Left}" />
-      </Style>
-
       <Style Selector="^ /template/ LayoutTransformControl#PART_ToggleTransform">
         <Setter Property="LayoutTransform" Value="rotate(90deg)" />
-        <Setter Property="HorizontalAlignment" Value="Left" />
+        <Setter Property="DockPanel.Dock" Value="Left"/>
+      </Style>
+      <Style Selector="^ /template/ controls|ContentExpandControl#PART_ContentExpand">
+        <Setter Property="Orientation" Value="Horizontal"/>
+        <Setter Property="HorizontalAlignment" Value="Left"/>
       </Style>
-
       <Style Selector="^ /template/ ToggleButton#PART_ToggleButton">
         <Setter Property="Theme" Value="{StaticResource RightExpanderToggleButtonPart}" />
       </Style>
@@ -256,4 +239,4 @@
 
   <ControlTheme x:Key="{x:Type Expander}" TargetType="Expander"
                 BasedOn="{StaticResource MaterialExpander}" />
-</ResourceDictionary>
+</ResourceDictionary>
\ No newline at end of file

From d7cf9d90f1b30dd61a3599099ea8b8dd76151c06 Mon Sep 17 00:00:00 2001
From: Sebastian Klatte <sebastian.klatte@qonlab.com>
Date: Sun, 29 Mar 2026 17:21:53 +0200
Subject: [PATCH 4/5] Remove unused imports.

---
 Material.Avalonia.Demo/Pages/ExpandersDemo.axaml | 1 -
 Material.Styles/Resources/Themes/Expander.axaml  | 3 +--
 2 files changed, 1 insertion(+), 3 deletions(-)

diff --git a/Material.Avalonia.Demo/Pages/ExpandersDemo.axaml b/Material.Avalonia.Demo/Pages/ExpandersDemo.axaml
index 7c7fd93c..e090c677 100644
--- a/Material.Avalonia.Demo/Pages/ExpandersDemo.axaml
+++ b/Material.Avalonia.Demo/Pages/ExpandersDemo.axaml
@@ -2,7 +2,6 @@
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
-             xmlns:assists="clr-namespace:Material.Styles.Assists;assembly=Material.Styles"
              xmlns:viewModels="clr-namespace:Material.Avalonia.Demo.ViewModels"
              mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
              x:Class="Material.Avalonia.Demo.Pages.ExpandersDemo"
diff --git a/Material.Styles/Resources/Themes/Expander.axaml b/Material.Styles/Resources/Themes/Expander.axaml
index eebdc349..a2a1980b 100644
--- a/Material.Styles/Resources/Themes/Expander.axaml
+++ b/Material.Styles/Resources/Themes/Expander.axaml
@@ -1,8 +1,7 @@
 <ResourceDictionary xmlns="https://github.com/avaloniaui"
                     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                     xmlns:assists="clr-namespace:Material.Styles.Assists"
-                    xmlns:controls="clr-namespace:Material.Styles.Controls"
-                    xmlns:converters="clr-namespace:Material.Styles.Converters">
+                    xmlns:controls="clr-namespace:Material.Styles.Controls">
 
   <ControlTheme x:Key="ExpanderToggleButtonPart" TargetType="ToggleButton">
     <Setter Property="Background" Value="Transparent" />

From 53893e1b9829b22f167423d538d30531d5d689eb Mon Sep 17 00:00:00 2001
From: Sebastian Klatte <sebastian.klatte@qonlab.com>
Date: Mon, 30 Mar 2026 00:17:50 +0200
Subject: [PATCH 5/5] Add dynamic header height demo.

---
 Material.Avalonia.Demo/Pages/ExpandersDemo.axaml | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/Material.Avalonia.Demo/Pages/ExpandersDemo.axaml b/Material.Avalonia.Demo/Pages/ExpandersDemo.axaml
index e090c677..91c03396 100644
--- a/Material.Avalonia.Demo/Pages/ExpandersDemo.axaml
+++ b/Material.Avalonia.Demo/Pages/ExpandersDemo.axaml
@@ -32,10 +32,16 @@
                   Content="{Binding }"
                   ContentTemplate="{StaticResource LoremContentTemplate}"/>
         
-        <Expander Header="This expander inflates content from upside!"
-                  ExpandDirection="Up"
+        <Expander ExpandDirection="Up"
                   Content="{Binding }"
-                  ContentTemplate="{StaticResource LoremContentTemplate}"/>
+                  ContentTemplate="{StaticResource LoremContentTemplate}">
+          <Expander.Header>
+            <StackPanel Spacing="8">
+              <TextBlock Text="This expander inflates content from upside!" FontSize="20" FontWeight="Bold" />
+              <TextBlock Text="And the header height adjusts dynamically" FontSize="14" />
+            </StackPanel>
+          </Expander.Header>
+        </Expander>
         
         <StackPanel Orientation="Horizontal">
             <Expander Header="Inflates left!"