This sample is to display the vertical line in the background of the chart. 
GridLine
direction: horizontal - horizontal line, vertical - vertical line, both - horizontal line + vertical line
verticalChangeCount: Filling the color by using verticalFill and verticalAlternateFill alternately 
by the number of times set as the value of the verticalChangeCount property.
verticalStroke: The color of the line between verticalFill and verticalAlternateFill.
verticalFill: The initial fill color.
verticalAlternateFill: The alternate fill color.

ā—¸Layout
<backgroundElements>
	<GridLines direction="vertical" verticalChangeCount="1" horizontalShowOrigin="false">
		<verticalStroke>
			<Stroke color="0xFF9966" alpha="0.5" weight="1"/>
			color:sets color, alpha: sets transparency, weight: sets thickness
		</verticalStroke>
		<verticalFill>
			<SolidColor color="0xFFCC99" alpha="0.5"/>
			color:sets color, alpha: sets transparency
		</verticalFill>
		<verticalAlternateFill>
			<SolidColor color="0xFFFFCC" alpha="0.5"/>
			color:sets color, alpha: sets transparency
		</verticalAlternateFill>
	</GridLines>
</backgroundElements>