Controlling ScrollViewer's vertical scrollbar height - wpf

Question

I need to make the vertical scrollbar a bit lower (shorter) because I need a space for a little button The button will be hovered over the ScrollViewer in the upper right corner. I would like to avoid separating the scrollbar out of the ScrollViewer just to add my button there.
It's a standard WPF ScrollViewer with
<ScrollViewer Name="Scroller" CanContentScroll="True" VerticalScrollBarVisibility="Auto" Height="{Binding ElementName=OuterContainer, Path=ActualHeight}" Width="{Binding ElementName=OuterContainer, Path=ActualWidth}">
<Grid Name="Container" Margin="5,5,5,5">
</Grid>
</ScrollViewer>
Is there any way I can style (or C# code) some hack which will free some space (it would be top margin, I guess) above the vertical scrollbar?

Answer 1

I would change the ScrollViewers style. According to the MSDN library http://msdn.microsoft.com/en-us/library/aa970847.aspx the default style is
<Style x:Key="LeftScrollViewer"
TargetType="{x:Type ScrollViewer}">
<Setter Property="OverridesDefaultStyle"
Value="True" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ScrollViewer}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Border Grid.Column="1"
BorderThickness="0,1,1,1">
<Border.BorderBrush>
<SolidColorBrush Color="{DynamicResource BorderMediumColor}" />
</Border.BorderBrush>
<ScrollContentPresenter />
</Border>
<ScrollBar x:Name="PART_VerticalScrollBar"
Value="{TemplateBinding VerticalOffset}"
Maximum="{TemplateBinding ScrollableHeight}"
ViewportSize="{TemplateBinding ViewportHeight}"
Visibility="{TemplateBinding ComputedVerticalScrollBarVisibility}"/>
<ScrollBar x:Name="PART_HorizontalScrollBar"
Orientation="Horizontal"
Grid.Row="1"
Grid.Column="1"
Value="{TemplateBinding HorizontalOffset}"
Maximum="{TemplateBinding ScrollableWidth}"
ViewportSize="{TemplateBinding ViewportWidth}"
Visibility="{TemplateBinding ComputedHorizontalScrollBarVisibility}"/>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
So you could replace the vertical scroll bar as
<ScrollBar x:Name="PART_VerticalScrollBar"
Value="{TemplateBinding VerticalOffset}"
Maximum="{TemplateBinding ScrollableHeight}"
ViewportSize="{TemplateBinding ViewportHeight}"
Visibility="{TemplateBinding ComputedVerticalScrollBarVisibility}"
**Margin="0,12,0,0"**/>