Why isn't my ScrollViewer scrolling?
My `ScrollViewer` is not working.  I've created a `UserControl` to show arrow indicators that tell the user that the scroll viewer can be scrolled.  So now, the content just overflows the `ScrollViewer`.  Here is my XAML:


    <UserControl x:Class="QCK.Common.ResourceLibrary.CustomControls.ArrowScrollViewer"
                 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                 xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
                 xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
                 mc:Ignorable="d" 
                 d:DesignHeight="300" d:DesignWidth="300"
                 Name="UserControl">
        <UserControl.Resources>
            
            <Style x:Key="ScrollDownArror" TargetType="{x:Type Border}">
                <Setter Property="Margin" Value="2,0,18,0"/>
                <Setter Property="Visibility" Value="Visible"/>
                <Style.Triggers>
                    <DataTrigger Binding="{Binding Path=CanScrollDown}" Value="True">
                        <Setter Property="Visibility" Value="Visible"/>
                    </DataTrigger>
                </Style.Triggers>
            </Style>
    
            <Style x:Key="ScrollUpArror" TargetType="{x:Type Border}">
                <Setter Property="Margin" Value="2,0,18,0"/>
                <Setter Property="Visibility" Value="Visible"/>
                <Style.Triggers>
                    <DataTrigger Binding="{Binding Path=CanScrollUp}" Value="True">
                        <Setter Property="Visibility" Value="Visible"/>
                    </DataTrigger>
                </Style.Triggers>
            </Style>
    
        </UserControl.Resources>
        <Grid>
            <ScrollViewer Name="scrollViewer" VerticalScrollBarVisibility="Visible">
                <ContentPresenter VerticalAlignment="Top"/>
            </ScrollViewer>
    
            <Border Style="{StaticResource ScrollUpArror}"  DataContext="{Binding ElementName=c_list}"
                                    IsHitTestVisible="false"
                                    VerticalAlignment="Top">
                <Image Margin="15" Height="20">
                    <Image.Source>
                        <DrawingImage>
                            <DrawingImage.Drawing>
                                <GeometryDrawing Brush="DarkGray" Geometry="M  0, 10 L 50, 30 L 100, 10 Z">
                                    <GeometryDrawing.Pen>
                                        <Pen Brush="DimGray" />
                                    </GeometryDrawing.Pen>
                                </GeometryDrawing>
                            </DrawingImage.Drawing>
                        </DrawingImage>
                    </Image.Source>
                </Image>
            </Border>
    
            <Border Style="{StaticResource ScrollDownArror}"  DataContext="{Binding ElementName=c_list}"
                                    IsHitTestVisible="false"
                                    VerticalAlignment="Bottom">
                <Image Margin="15" Height="20">
                    <Image.Source>
                        <DrawingImage>
                            <DrawingImage.Drawing>
                                <GeometryDrawing Brush="DarkGray" Geometry="M  0, 30 L 50, 10 L 100, 30 Z">
                                    <GeometryDrawing.Pen>
                                        <Pen Brush="DimGray" />
                                    </GeometryDrawing.Pen>
                                </GeometryDrawing>
                            </DrawingImage.Drawing>
                        </DrawingImage>
                    </Image.Source>
                </Image>
            </Border>
        </Grid>
    </UserControl>

The contents just overflow inside the control not showing a scroll bar or allowing mouse wheel scrolling or anything.  
Why isn't my ScrollViewer scrolling?
===

My `ScrollViewer` is not working.  I've created a `UserControl` to show arrow indicators that tell the user that the scroll viewer can be scrolled.  So now, the content just overflows the `ScrollViewer`.  Here is my XAML:


    <UserControl x:Class="QCK.Common.ResourceLibrary.CustomControls.ArrowScrollViewer"
                 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                 xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
                 xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
                 mc:Ignorable="d" 
                 d:DesignHeight="300" d:DesignWidth="300"
                 Name="UserControl">
        <UserControl.Resources>
            
            <Style x:Key="ScrollDownArror" TargetType="{x:Type Border}">
                <Setter Property="Margin" Value="2,0,18,0"/>
                <Setter Property="Visibility" Value="Visible"/>
                <Style.Triggers>
                    <DataTrigger Binding="{Binding Path=CanScrollDown}" Value="True">
                        <Setter Property="Visibility" Value="Visible"/>
                    </DataTrigger>
                </Style.Triggers>
            </Style>
    
            <Style x:Key="ScrollUpArror" TargetType="{x:Type Border}">
                <Setter Property="Margin" Value="2,0,18,0"/>
                <Setter Property="Visibility" Value="Visible"/>
                <Style.Triggers>
                    <DataTrigger Binding="{Binding Path=CanScrollUp}" Value="True">
                        <Setter Property="Visibility" Value="Visible"/>
                    </DataTrigger>
                </Style.Triggers>
            </Style>
    
        </UserControl.Resources>
        <Grid>
            <ScrollViewer Name="scrollViewer" VerticalScrollBarVisibility="Visible">
                <ContentPresenter VerticalAlignment="Top"/>
            </ScrollViewer>
    
            <Border Style="{StaticResource ScrollUpArror}"  DataContext="{Binding ElementName=c_list}"
                                    IsHitTestVisible="false"
                                    VerticalAlignment="Top">
                <Image Margin="15" Height="20">
                    <Image.Source>
                        <DrawingImage>
                            <DrawingImage.Drawing>
                                <GeometryDrawing Brush="DarkGray" Geometry="M  0, 10 L 50, 30 L 100, 10 Z">
                                    <GeometryDrawing.Pen>
                                        <Pen Brush="DimGray" />
                                    </GeometryDrawing.Pen>
                                </GeometryDrawing>
                            </DrawingImage.Drawing>
                        </DrawingImage>
                    </Image.Source>
                </Image>
            </Border>
    
            <Border Style="{StaticResource ScrollDownArror}"  DataContext="{Binding ElementName=c_list}"
                                    IsHitTestVisible="false"
                                    VerticalAlignment="Bottom">
                <Image Margin="15" Height="20">
                    <Image.Source>
                        <DrawingImage>
                            <DrawingImage.Drawing>
                                <GeometryDrawing Brush="DarkGray" Geometry="M  0, 30 L 50, 10 L 100, 30 Z">
                                    <GeometryDrawing.Pen>
                                        <Pen Brush="DimGray" />
                                    </GeometryDrawing.Pen>
                                </GeometryDrawing>
                            </DrawingImage.Drawing>
                        </DrawingImage>
                    </Image.Source>
                </Image>
            </Border>
        </Grid>
    </UserControl>

The contents just overflow inside the control not showing a scroll bar or allowing mouse wheel scrolling or anything.  