Bug 312531 Highlight works differently when run SvgInteractivityViewer.java [13]
chart/org.eclipse.birt.chart.device.svg/src/org/eclipse/birt/chart/device/svg/SVGGraphics2D.java
protected Element createGradientPaint( SVGGradientPaint paint,
			boolean highlight )
	{
		Element elem = dom.createElement( "linearGradient" ); 
		if ( highlight )
			elem.setAttribute( "id", paint.getId( ) + "h" ); 
		else
			elem.setAttribute( "id", paint.getId( ) ); 
		elem.setAttribute( "x1", toString( paint.getPoint1( ).getX( ) ) ); 
		elem.setAttribute( "y1", toString( paint.getPoint1( ).getY( ) ) ); 
		elem.setAttribute( "x2", toString( paint.getPoint2( ).getX( ) ) ); 
		elem.setAttribute( "y2", toString( paint.getPoint2( ).getY( ) ) ); 
		elem.setAttribute( "gradientUnits", "userSpaceOnUse" ); 
		if ( paint.isCyclic( ) )
			elem.setAttribute( "spreadMethod", "repeat" ); 
		Element startColor = dom.createElement( "stop" ); 
		startColor.setAttribute( "offset", "0%" ); 
		if ( highlight )
		{
			startColor.setAttribute( "stop-color", serializeHighlightToString( paint.getColor1( ) ) ); 
		}
		else
		{
			startColor.setAttribute( "stop-color", serializeToString( paint.getColor1( ) ) ); 
		}
		String alpha = alphaToString( paint.getColor1( ) );
		if ( alpha != null )
			startColor.setAttribute( "stop-opacity", alpha ); 
		elem.appendChild( startColor );
		Element endColor = dom.createElement( "stop" );