AddSub.xaml

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
	<DrawingBrush x:Key="Add" Stretch="Uniform">
		<DrawingBrush.Drawing>
			<DrawingGroup>
				<DrawingGroup.Children>
					<GeometryDrawing Brush="{DynamicResource UiElementForeground}" Geometry="F1 M 35,19L 41,19L 41,35L 57,35L 57,41L 41,41L 41,57L 35,57L 35,41L 19,41L 19,35L 35,35L 35,19 Z "/>
				</DrawingGroup.Children>
			</DrawingGroup>
		</DrawingBrush.Drawing>
	</DrawingBrush>
</ResourceDictionary>