VB.net 2010 - WPF Datagrid Cell Background Style Issue

So, I am trying to setup a datatrigger for a datagridcell in WPF that shows a red square when the cell contains the word "red". It works but the problem is I am modifying the background and when the row is selected it shows a white box around the square. I want to get rid of the white box and I have been looking for another way of going about what I want but can't figure it out. Below is the code and an example image.

Code:

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    <Style x:Key="dgJobsPriority" TargetType="DataGridCell">
        <Style.Triggers>
            <DataTrigger Binding="{Binding Priority}" Value="Red">
                <Setter Property="Background">
                    <Setter.Value>
                        <DrawingBrush Stretch="None">
                            <DrawingBrush.Drawing>
                                <DrawingGroup>
                                    <GeometryDrawing Brush="Red">
                                        <GeometryDrawing.Geometry>
                                            <RectangleGeometry Rect="0,0,16,16" />
                                        </GeometryDrawing.Geometry>
                                    </GeometryDrawing>
                                </DrawingGroup>
                            </DrawingBrush.Drawing>
                        </DrawingBrush>
                    </Setter.Value>
                    </Setter>
            </DataTrigger>
        </Style.Triggers>
        <Setter Property="Foreground" Value="#00000000"/>
    </Style>

---

Attachment 100547

Of course I figure it out not long after I post this ... so annoying when that happens. If anyone could provide some insight if this is an "acceptable" way of doing this or if there is a "better" way I would appreciate the input. WPF seems so powerful but also so confusing for just being markup at times.

Code:

---

    <Style x:Key="dgJobsPriority" TargetType="DataGridCell">
        <Style.Triggers>
            <DataTrigger Binding="{Binding Priority}" Value="Red">
                <Setter Property="Template">
                    <Setter.Value>
                        <ControlTemplate TargetType="{x:Type DataGridCell}">
                            <Grid Background="{TemplateBinding Background}">
                                <Canvas>
                                    <Rectangle Width="16" Height="16" Fill="Red" Canvas.Left="3" Canvas.Top="3" />
                                </Canvas>
                            </Grid>
                        </ControlTemplate>
                    </Setter.Value>
                </Setter>
            </DataTrigger>
        </Style.Triggers>
    </Style>

---

Is it not a margin or a padding?