Content control contents sizing to fill in Silverlight 4 - silverlight

Question

I have a style for a ContentControl which I want to use in places where I currently have a Border. When I use this, the child controls will not stretch to fill and only take a small amount of space. I've tried applying HorizontalAlignment="Stretch" to everything, but it doesn't work. What's wrong?
<Style x:Key="GradientPanel" TargetType="ContentControl">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ContentControl">
<Grid HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}">
<Rectangle RadiusY="10" RadiusX="10" Stroke="Black" StrokeThickness="0">
<Rectangle.Effect>
<DropShadowEffect Opacity="0.56" ShadowDepth="1" BlurRadius="3" />
</Rectangle.Effect>
<Rectangle.Fill>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#FFE1EAF3"/>
<GradientStop Color="White" Offset="1"/>
<GradientStop Color="#FFFAFBFD" Offset="1"/>
</LinearGradientBrush>
</Rectangle.Fill>
</Rectangle>
<ContentPresenter Margin="5" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"/>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
...
Before (works fine):
<Border Style="{StaticResource SearchContainerBorder}" >
<Grid Margin="5">
<Grid.RowDefinitions>
<RowDefinition />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="Auto" />
</Grid.ColumnDefinitions>
<ToggleButton Style="{StaticResource ToggleButtonExpanderStyle}" Grid.Row="0" Grid.Column="1" Height="25" Width ="25" HorizontalAlignment="Center" VerticalAlignment="Top" />
<ContentControl Grid.Row="0" HorizontalContentAlignment="Stretch" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"/>
</Grid>
</Border>
After (replace Border with ContentControl):
<ContentControl Style="{StaticResource GradPanel}" HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
<Grid Margin="5">
<Grid.RowDefinitions>
<RowDefinition />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="Auto" />
</Grid.ColumnDefinitions>
<ToggleButton Style="{StaticResource ToggleButtonExpanderStyle}" Grid.Row="0" Grid.Column="1" Height="25" Width ="25" HorizontalAlignment="Center" VerticalAlignment="Top" />
<ContentControl Grid.Row="0" HorizontalContentAlignment="Stretch" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"/>
</Grid>
</ContentControl>

Answer 1

You need to set the HorizontalContentAlignment="Stretch" and the VerticalContentAlignment="Stretch" settings on your outer ContentControl.
The default behaviour is to NOT stretch the contents of a container.
e.g. the first line should be:
<ContentControl Style="{StaticResource GradPanel}"
HorizontalAlignment="Stretch"
VerticalAlignment="Stretch"
HorizontalContentAlignment="Stretch"
VerticalContentAlignment="Stretch" >