To draw Horizontal
************************
<Rectangle HorizontalAlignment="Stretch" VerticalAlignment="Center" Fill="DarkCyan" Height="4"/>
To draw vertical
*******************
<Rectangle HorizontalAlignment="Stretch" VerticalAlignment="Center" Fill="DarkCyan" Height="4" Width="Auto" >
<Rectangle.RenderTransform>
<TransformGroup>
<ScaleTransform/>
<SkewTransform/>
<RotateTransform Angle="90"/>
<TranslateTransform/>
</TransformGroup>
</Rectangle.RenderTransform>
</Rectangle>