CoverFlow non-selected Game Opacity Property

[nicolasonline]

Can anyone help with the syntax/code of adding a change to opacity for non-selected games in the CoverFlow view?

I am nearly done with my custom theme for the new 11.10 but the default non-selected CoverFlow games are too dark for the white background so would like to reduce opacity to around 0.33. I tried using <coverFlow:FlowControl.OpacityMask><Brush> as well as Style Triggers but keep getting errors. Is there a simpler way to do this?

Thanks a lot!

                <coverFlow:FlowControl x:Name="FlowControl" Grid.Row="0" Grid.Column="0" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"
                    Opacity="1" ImageType="Boxes" VisibleCount="10" PageSize="0" CameraZPosition="3"
                    CoverFactory="{Binding CoverFactory}" RenderTransformOrigin=".5,.5" >
                    <coverFlow:FlowControl.RenderTransform>
                        <TransformGroup>
                            <RotateTransform Angle="0" />
                            <ScaleTransform ScaleX="1" ScaleY="1" />
                            <SkewTransform  AngleX="0" AngleY="0" />
                        </TransformGroup>
                    </coverFlow:FlowControl.RenderTransform>
                        
                </coverFlow:FlowControl>