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
endColor.setAttribute( "offset", "100%" ); 
		if ( highlight )
			endColor.setAttribute( "stop-color", serializeHighlightToString( paint.getColor2( ) ) ); 			
		else
			endColor.setAttribute( "stop-color", serializeToString( paint.getColor2( ) ) ); 
		alpha = alphaToString( paint.getColor2( ) );
		if ( alpha != null )
			endColor.setAttribute( "stop-opacity", alpha ); 
		elem.appendChild( endColor );
		return elem;
	}
	
	private String getTextureId( TexturePaint paint )
	{
		return "tp" + paint.hashCode( ); 
	}
	protected Element createTexturePaint( TexturePaint paint, String imgId,
			boolean highlight )
	{
		Element elem = dom.createElement( "pattern" ); 
		if ( highlight )
			elem.setAttribute( "id", getTextureId( paint ) + "h" ); 
		else
			elem.setAttribute( "id", getTextureId( paint ) ); 
		
		BufferedImage img = paint.getImage( );
		int width = img.getWidth( );
		int height = img.getHeight( );
		elem.setAttribute( "patternUnits", "userSpaceOnUse" );
		elem.setAttribute( "width", Integer.toString( width ) );