test.xaml

<Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition/>
            <ColumnDefinition/>
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition/>
            <RowDefinition Height="Auto" />
            <RowDefinition MinHeight="70"/>
        </Grid.RowDefinitions>
        <GridSplitter HorizontalAlignment="Stretch" Height="10" Margin="0" VerticalAlignment="Stretch" Grid.Row="1" ResizeDirection="Rows"/>
        <DockPanel Margin="0">
            <Label Content="Display" Height="30" Background="#FF7A1322" Foreground="White" DockPanel.Dock="Top"/>
            <RichTextBox Background="#FFB2B2B2" DockPanel.Dock="Bottom" IsReadOnly="True" />
        </DockPanel>
    </Grid>