CommandControl.xaml

<UserControl x:Class="WinDbgExt.History.CommandControl"
             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">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition />
            <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>

        <RichTextBox x:Name="ContentTextBox" FontFamily="Consolas" Grid.Row="0" IsDocumentEnabled="True" VerticalScrollBarVisibility="Visible" IsReadOnly="True">
            <RichTextBox.Document>
                <FlowDocument></FlowDocument>
            </RichTextBox.Document>
        </RichTextBox>
        <TextBox x:Name="CommandTextBox" Grid.Row="1" KeyDown="CommandTextBox_KeyDown" />
    </Grid>
</UserControl>