If I have a user control defined:

public partial class MainFooter : UserControl
{
    public System.Windows.Media.Color BkColor;
}

and it's xaml:

<UserControl x:Class="Test.MainFooter">
    <Grid x:Name="LayoutRoot">
        <Rectangle x:Name="rctBottom_Background2"
                   HorizontalAlignment="Stretch" 
                   Grid.Row="2">
            <Rectangle.Fill>
                <LinearGradientBrush EndPoint="0.82,0.895" StartPoint="0.911,-0.442">
                    <GradientStop Color="{**How can I bind this to the BkColor property?}"/**>
                    <GradientStop Color="#00FFFFFF" Offset="1"/>
                </LinearGradientBrush>
            </Rectangle.Fill>
        </Rectangle>
    </Grid>
</UserControl>

and used:

<MyControls:MainFooter x:Name="rcrMainFooter"
                       BkColor="#FFE2B42A">
</MyControls:MainFooter>

How would I go about binding the GradientStop Color in the Rectangle to the value of the it's user controls BkColor property?