Bug 176582 "Show Lines as Curves" does not work correctly for Area Chart [0001]
Description: "Show Lines as Curves" does not work correctly for Area Chart. Build number: 2.2.0.v20070307-1128 Steps to reproduce: 1. New a Area Chart. 2. In "Format Chart" tab, select Series->Value (Y) Series, tick and untick "Show Lines as Curves" checkbox. Expected result: Null value point e is treated the same when tick and untick "Show Lines as Curves" checkbox. Actual result: Null value point e is treated differently (see the screenshot). Error log: N/A
chart/org.eclipse.birt.chart.engine/src/org/eclipse/birt/chart/render/CurveRenderer.java
faKnotXY1[0] = faKnotXY2[0];
			faKnotXY1[1] = faKnotXY2[1];
		}
		if ( bFillArea )
		{
			plotArea( ipr, stateList );
		}
		if ( bKeepState )
		{
			if ( iRender instanceof AxesRenderer
					&& ( (AxesRenderer) iRender ).isLastRuntimeSeriesInAxis( ) )
			{
				
				iRender.getRunTimeContext( )
						.putState( BaseRenderer.STACKED_SERIES_LOCATION_KEY,
								null );
			}
			else
			{
				iRender.getRunTimeContext( )
						.putState( BaseRenderer.STACKED_SERIES_LOCATION_KEY,
								stateList );
			}
		}
	}
	/**
	 * Spline
	 */
	private static class Spline
	{