How to make Richtextblock scrollable?

Question

<StackPanel Orientation="Vertical">  
<Border Background="AliceBlue">
    <ScrollViewer x:Name="scroll"                              
                  Height="300"
                  AllowDrop="True"
                  HorizontalScrollBarVisibility="Visible"
                  VerticalScrollBarVisibility="Visible"
                  VerticalScrollMode="Auto">

        <RichTextBlock x:Name="richTextBlock"
                       Width="800"
                       Height="400"
                       Margin="50 50 0 0"
                       Foreground="Green">
            <Paragraph x:Name="rchparaGraph">
                <Run />
            </Paragraph>
        </RichTextBlock>
    </ScrollViewer>
</Border>

this is how i have align the control. i have used scroll viewer for making rich text block scrollable to its content. Its not working. somebody help me.

Answer 1

Remove your ScrollViewer and Make ScrollViewer.VerticalScrollBarVisibility="Auto" inside RichTextBox

<RichTextBox ScrollViewer.VerticalScrollBarVisibility="Auto">

EDIT:

<ScrollViewer Name="scroll"
              Margin="0"
              VerticalAlignment="Top"
              VerticalScrollBarVisibility="Hidden"
              Background="#CC000000"
              HorizontalScrollBarVisibility="Disabled">
             <StackPanel Orientation="Vertical"
                VerticalAlignment="Top"
                Margin="0">
             <RichTextBlock x:Name="richTextBlock"
                     Height="100"
                     HorizontalAlignment="Left"
                     VerticalAlignment="Center">
             <Paragraph>
                <Run />
             </Paragraph>
        </RichTextBlock>