From e7f80f7acea318c661708dbe0c8292c7be220fd0 Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@gmail.com>
Date: Wed, 23 Sep 2020 10:50:36 +0200
Subject: [PATCH 1/3] Correctly style submenu scrollers.

---
 src/Avalonia.Themes.Default/MenuItem.xaml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Avalonia.Themes.Default/MenuItem.xaml b/src/Avalonia.Themes.Default/MenuItem.xaml
index 7d7d06dd55..741cf1b79c 100644
--- a/src/Avalonia.Themes.Default/MenuItem.xaml
+++ b/src/Avalonia.Themes.Default/MenuItem.xaml
@@ -64,7 +64,7 @@
               <Border Background="{TemplateBinding Background}"
                       BorderBrush="{DynamicResource ThemeBorderMidBrush}"
                       BorderThickness="{TemplateBinding BorderThickness}">
-                <ScrollViewer>                  
+                <ScrollViewer Classes="menuscroller">                  
                     <ItemsPresenter Name="PART_ItemsPresenter"
                                     Items="{TemplateBinding Items}"
                                     ItemsPanel="{TemplateBinding ItemsPanel}"

From 4a1db02d7d75bcfb997485f33951d6093437662f Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@gmail.com>
Date: Wed, 23 Sep 2020 11:33:39 +0200
Subject: [PATCH 2/3] Style fluent menu scrollers.

---
 src/Avalonia.Themes.Fluent/ContextMenu.xaml  |  2 +-
 src/Avalonia.Themes.Fluent/MenuItem.xaml     |  4 +-
 src/Avalonia.Themes.Fluent/ScrollViewer.xaml | 64 +++++++++++++++++++-
 3 files changed, 66 insertions(+), 4 deletions(-)

diff --git a/src/Avalonia.Themes.Fluent/ContextMenu.xaml b/src/Avalonia.Themes.Fluent/ContextMenu.xaml
index 6ad038676b..33447ffd6c 100644
--- a/src/Avalonia.Themes.Fluent/ContextMenu.xaml
+++ b/src/Avalonia.Themes.Fluent/ContextMenu.xaml
@@ -49,7 +49,7 @@
               MinHeight="{TemplateBinding MinHeight}"
               HorizontalAlignment="{TemplateBinding HorizontalAlignment}"
               CornerRadius="{DynamicResource OverlayCornerRadius}">
-        <ScrollViewer>
+        <ScrollViewer Classes="menuscroller">
           <ItemsPresenter Name="PART_ItemsPresenter"
                           Items="{TemplateBinding Items}"
                           ItemsPanel="{TemplateBinding ItemsPanel}"
diff --git a/src/Avalonia.Themes.Fluent/MenuItem.xaml b/src/Avalonia.Themes.Fluent/MenuItem.xaml
index 3a03ec1acf..1f1dcf22e2 100644
--- a/src/Avalonia.Themes.Fluent/MenuItem.xaml
+++ b/src/Avalonia.Themes.Fluent/MenuItem.xaml
@@ -123,7 +123,7 @@
                     MinHeight="{DynamicResource MenuFlyoutThemeMinHeight}"
                     HorizontalAlignment="Stretch"
                     CornerRadius="{DynamicResource OverlayCornerRadius}">
-              <ScrollViewer>
+              <ScrollViewer Classes="menuscroller">
                 <ItemsPresenter Name="PART_ItemsPresenter"
                                 Items="{TemplateBinding Items}"
                                 ItemsPanel="{TemplateBinding ItemsPanel}"
@@ -171,7 +171,7 @@
                       MinHeight="{DynamicResource MenuFlyoutThemeMinHeight}"
                       HorizontalAlignment="Stretch"
                       CornerRadius="{DynamicResource OverlayCornerRadius}">
-                <ScrollViewer>
+                <ScrollViewer Classes="menuscroller">
                   <ItemsPresenter Name="PART_ItemsPresenter"
                                   Items="{TemplateBinding Items}"
                                   ItemsPanel="{TemplateBinding ItemsPanel}"
diff --git a/src/Avalonia.Themes.Fluent/ScrollViewer.xaml b/src/Avalonia.Themes.Fluent/ScrollViewer.xaml
index fb73f7eab1..e36eb5e77c 100644
--- a/src/Avalonia.Themes.Fluent/ScrollViewer.xaml
+++ b/src/Avalonia.Themes.Fluent/ScrollViewer.xaml
@@ -1,4 +1,6 @@
-<Styles xmlns="https://github.com/avaloniaui" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+<Styles xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:converters="clr-namespace:Avalonia.Controls.Converters;assembly=Avalonia.Controls">
 
   <Style Selector="ScrollViewer">
     <Setter Property="Background"
@@ -66,4 +68,64 @@
     <Setter Property="Opacity" Value="1" />
   </Style>
 
+  <Style Selector="ScrollViewer.menuscroller">
+    <Setter Property="Template">
+      <ControlTemplate>
+        <DockPanel>
+          <RepeatButton DockPanel.Dock="Top"
+                        BorderThickness="0"
+                        Background="Transparent"
+                        HorizontalAlignment="Stretch"
+                        HorizontalContentAlignment="Center"
+                        RenderTransform="{x:Null}"
+                        Command="{Binding LineUp, RelativeSource={RelativeSource TemplatedParent}}">
+            <RepeatButton.IsVisible>
+              <MultiBinding Converter="{x:Static converters:MenuScrollingVisibilityConverter.Instance}"
+                            ConverterParameter="0">
+                <Binding RelativeSource="{RelativeSource TemplatedParent}" Path="VerticalScrollBarVisibility"/>
+                <Binding RelativeSource="{RelativeSource TemplatedParent}" Path="Offset.Y"/>
+                <Binding RelativeSource="{RelativeSource TemplatedParent}" Path="Extent.Height"/>
+                <Binding RelativeSource="{RelativeSource TemplatedParent}" Path="Viewport.Height"/>
+              </MultiBinding>
+            </RepeatButton.IsVisible>
+            <Path Data="M 0 4 L 8 4 L 4 0 Z"/>
+          </RepeatButton>
+          <RepeatButton DockPanel.Dock="Bottom"
+                        BorderThickness="0"
+                        Background="Transparent"
+                        HorizontalAlignment="Stretch"
+                        HorizontalContentAlignment="Center"
+                        RenderTransform="{x:Null}"
+                        Command="{Binding LineDown, RelativeSource={RelativeSource TemplatedParent}}">
+            <RepeatButton.IsVisible>
+              <MultiBinding Converter="{x:Static converters:MenuScrollingVisibilityConverter.Instance}"
+                            ConverterParameter="100">
+                <Binding RelativeSource="{RelativeSource TemplatedParent}" Path="VerticalScrollBarVisibility"/>
+                <Binding RelativeSource="{RelativeSource TemplatedParent}" Path="Offset.Y"/>
+                <Binding RelativeSource="{RelativeSource TemplatedParent}" Path="Extent.Height"/>
+                <Binding RelativeSource="{RelativeSource TemplatedParent}" Path="Viewport.Height"/>
+              </MultiBinding>
+            </RepeatButton.IsVisible>
+            <Path Data="M 0 0 L 4 4 L 8 0 Z"/>
+          </RepeatButton>
+          <ScrollContentPresenter Name="PART_ContentPresenter"
+                                  CanHorizontallyScroll="{TemplateBinding CanHorizontallyScroll}"
+                                  CanVerticallyScroll="{TemplateBinding CanVerticallyScroll}"
+                                  Content="{TemplateBinding Content}"
+                                  Extent="{TemplateBinding Extent, Mode=TwoWay}"
+                                  Margin="{TemplateBinding Padding}"
+                                  Offset="{TemplateBinding Offset, Mode=TwoWay}"
+                                  Viewport="{TemplateBinding Viewport, Mode=TwoWay}"/>
+        </DockPanel>
+      </ControlTemplate>
+    </Setter>
+  </Style>
+  <Style Selector="ScrollViewer.menuscroller /template/ RepeatButton > Path">
+    <Setter Property="Fill" Value="{DynamicResource ScrollBarButtonArrowForeground}" />
+  </Style>
+
+  <Style Selector="ScrollViewer.menuscroller /template/ RepeatButton:pointerover > Path">
+    <Setter Property="Fill" Value="{DynamicResource ScrollBarButtonArrowForegroundPointerOver}" />
+  </Style>
+
 </Styles>

From f5c310e187f82f89878710497a47967d2909d428 Mon Sep 17 00:00:00 2001
From: Max Katz <maxkatz6@outlook.com>
Date: Sat, 26 Sep 2020 23:07:27 -0400
Subject: [PATCH 3/3] Fluent icons in ScrollViewer.menuscroller

---
 src/Avalonia.Themes.Fluent/ScrollViewer.xaml | 36 +++++++++++++++++---
 1 file changed, 32 insertions(+), 4 deletions(-)

diff --git a/src/Avalonia.Themes.Fluent/ScrollViewer.xaml b/src/Avalonia.Themes.Fluent/ScrollViewer.xaml
index e36eb5e77c..640b8de89f 100644
--- a/src/Avalonia.Themes.Fluent/ScrollViewer.xaml
+++ b/src/Avalonia.Themes.Fluent/ScrollViewer.xaml
@@ -2,6 +2,20 @@
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:converters="clr-namespace:Avalonia.Controls.Converters;assembly=Avalonia.Controls">
 
+  <Design.PreviewWith>
+    <Grid ColumnDefinitions="*,20,*"
+          Height="300"
+          Width="200"
+          Margin="20">
+      <ScrollViewer>
+        <Border Height="1000" Background="#ccc"/>
+      </ScrollViewer>
+      <ScrollViewer Grid.Column="2" Classes="menuscroller">
+        <Border Height="1000" Background="#ccc"/>
+      </ScrollViewer>
+    </Grid>
+  </Design.PreviewWith>
+  
   <Style Selector="ScrollViewer">
     <Setter Property="Background"
             Value="Transparent" />
@@ -88,7 +102,14 @@
                 <Binding RelativeSource="{RelativeSource TemplatedParent}" Path="Viewport.Height"/>
               </MultiBinding>
             </RepeatButton.IsVisible>
-            <Path Data="M 0 4 L 8 4 L 4 0 Z"/>
+            <Viewbox Width="{DynamicResource ScrollBarButtonArrowIconFontSize}"
+                     Height="{DynamicResource ScrollBarButtonArrowIconFontSize}">
+              <Path VerticalAlignment="Center"
+                    HorizontalAlignment="Center"
+                    Data="M 19.091797 14.970703 L 10 5.888672 L 0.908203 14.970703 L 0.029297 14.091797 L 10 4.111328 L 19.970703 14.091797 Z"
+                    Width="20"
+                    Height="20" />
+            </Viewbox>
           </RepeatButton>
           <RepeatButton DockPanel.Dock="Bottom"
                         BorderThickness="0"
@@ -106,7 +127,14 @@
                 <Binding RelativeSource="{RelativeSource TemplatedParent}" Path="Viewport.Height"/>
               </MultiBinding>
             </RepeatButton.IsVisible>
-            <Path Data="M 0 0 L 4 4 L 8 0 Z"/>
+            <Viewbox Width="{DynamicResource ScrollBarButtonArrowIconFontSize}"
+                     Height="{DynamicResource ScrollBarButtonArrowIconFontSize}">
+              <Path VerticalAlignment="Center"
+                    HorizontalAlignment="Center"
+                    Data="M 18.935547 4.560547 L 19.814453 5.439453 L 10 15.253906 L 0.185547 5.439453 L 1.064453 4.560547 L 10 13.496094 Z"
+                    Width="20"
+                    Height="20" />
+            </Viewbox>
           </RepeatButton>
           <ScrollContentPresenter Name="PART_ContentPresenter"
                                   CanHorizontallyScroll="{TemplateBinding CanHorizontallyScroll}"
@@ -120,11 +148,11 @@
       </ControlTemplate>
     </Setter>
   </Style>
-  <Style Selector="ScrollViewer.menuscroller /template/ RepeatButton > Path">
+  <Style Selector="ScrollViewer.menuscroller /template/ RepeatButton > Viewbox > Path">
     <Setter Property="Fill" Value="{DynamicResource ScrollBarButtonArrowForeground}" />
   </Style>
 
-  <Style Selector="ScrollViewer.menuscroller /template/ RepeatButton:pointerover > Path">
+  <Style Selector="ScrollViewer.menuscroller /template/ RepeatButton:pointerover > Viewbox > Path">
     <Setter Property="Fill" Value="{DynamicResource ScrollBarButtonArrowForegroundPointerOver}" />
   </Style>