TextBox in ScrollViewer problems

[CodingOctocat]

I have a TextBox in ScrollViewer, but it has some scrolling problems!

As shown in the following gif, if the TextBox is in a ScrollViewer, then if the currently edited line is at the bottom of the viewport and we enter a new line, it will scroll down so that the current line is still visible, but the scrolling is not at one line's height, which makes several pixels worth of content invisible.

How can this be resolved?

TextBoxTest.zip

<Window x:Class="TextBoxTest.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        Title="MainWindow"
        Width="800"
        Height="150"
        Background="Azure"
        FontSize="16"
        FontWeight="Bold"
        Topmost="True"
        mc:Ignorable="d">
    <UniformGrid Margin="12"
                 Columns="2"
                 Rows="1">
        <ScrollViewer Grid.Row="1"
                      CanContentScroll="True">
            <Grid>
                <Grid.RowDefinitions>
                    <RowDefinition Height="Auto" />
                    <RowDefinition />
                </Grid.RowDefinitions>

                <TextBlock Text="Scroll to current line incomplete" />

                <TextBox Grid.Row="1"
                         Padding="4"
                         AcceptsReturn="True" />
            </Grid>
        </ScrollViewer>

        <Grid>
            <Grid.RowDefinitions>
                <RowDefinition Height="Auto" />
                <RowDefinition />
            </Grid.RowDefinitions>

            <TextBlock Text="Normal" />

            <TextBox Grid.Row="1"
                     Padding="4"
                     AcceptsReturn="True" />
        </Grid>
    </UniformGrid>
</Window>