In WPF, how can I set a TextBox MaxHeight according to Two other controls
<StackPanel
                Name="stkOuter">
                <StackPanel
                    Name="stkInner">
                    Content...
                </StackPanel>
                <TextBox>
                    Content...
                </TextBox>
            </StackPanel>

stkOuter.ActualHeight-stkInner.ActualHeight

MaxHeight="{Binding RelativeSource={RelativeSource AncestorType={x:Type StackPanel}},
                    Path=ActualHeight,
                    Converter={StaticResource MyConverter},
                    ConverterParameter={WHAT GOES HERE?}}"

<TextBox.MaxHeight>
   <MultiBinding Converter={StaticResource myIMultiValueConverter}>
      <Binding /> <!-- bind the first value here -->
      <Binding /> <!-- bind the second value here -->
      ...
   </MultiBinding>
</TextBox.MaxHeight>