Problem using * in Grid sizes

Question

Hello

When I set a column's width or a row's height to star, and I fill in content that is bigger than the available rectangle, the row keeps on growing 'underground':

<Window x:Class="Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="100" Width="100">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition />
            <RowDefinition />
        </Grid.RowDefinitions>
        <StackPanel>
            <Button Content="Button" />
            <Button Content="Button" />
            <Button Content="Button" />
        </StackPanel>
        <StackPanel Grid.Row="1" 
                ScrollViewer.CanContentScroll="True" 
                ScrollViewer.VerticalScrollBarVisibility="Auto" 
                ScrollViewer.IsDeferredScrollingEnabled="True">
            <Button Content="Button" />
            <Button Content="Button" />
            <Button Content="Button" />
        </StackPanel>
    </Grid>
</Window>

I want that StackPanel should not grow underground, instead it should show scrollbars.

Note, I need all the size dynamic so everything changes according to the user resizing the parents.
I have the same issue with columns.
PS. RowDefinition.Height is always * by default.

UPDATE

I guess the problem is the grid and the previous snippet I posted didn't provide the whole story, please review:

<Window x:Class="Window1" 
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"            
Title="Window1" Height="200">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="20"/>
            <RowDefinition/>
            <RowDefinition Height="20"/>
        </Grid.RowDefinitions>
        <StackPanel Grid.Row="1">
            <StackPanel>
                <TextBlock Text="Hello"/>
                <TextBox Text="World!"/>
            </StackPanel>
            <ScrollViewer>
                <StackPanel>
                    <Button Content="Button"/>
                    <Button Content="Button"/>
                    <Button Content="Button"/>
                    <Button Content="Button"/>
                    <Button Content="Button"/>
                </StackPanel>
            </ScrollViewer>
        </StackPanel>
    </Grid>
</Window>

Answer 1

I'm not sure that StackPanel has a built in ScrollViewer so setting the ScrollViewer.* attached proeprties really has no effect on it.

Have you tried wrapping the StackPanel with a ScrollViewer explicitly? For example:

<ScrollViewer Grid.Row="1"
       ScrollViewer.CanContentScroll="True" 
       ScrollViewer.VerticalScrollBarVisibility="Auto" 
       ScrollViewer.IsDeferredScrollingEnabled="True">
    <StackPanel>
        <Button Content="Button" />
        <Button Content="Button" />
        <Button Content="Button" />
    </StackPanel>
</ScrollViewer>