Bug 188029 Top face is missing in Area chart of 2D+ with negative values
Top face is missing in Area chart of 2D+ with negative values. Please see attached screenshot.
chart/org.eclipse.birt.chart.engine/src/org/eclipse/birt/chart/computation/withaxes/StackedSeriesLookup.java
{
			sg.alUnitPositions = new ArrayList( 8 );
		}
		
		if ( sg.alUnitPositions.size( ) <= iUnitIndex )
		{
			sg.alUnitPositions.add( new AxisSubUnit( ) );
		}
		return (AxisSubUnit) sg.alUnitPositions.get( iUnitIndex );
	}
	/**
	 * 
	 */
	public final void resetSubUnits( )
	{
		Enumeration e = htSeriesToStackGroup.elements( );
		StackGroup sg;
		AxisSubUnit asu;
		while ( e.hasMoreElements( ) )
		{
			sg = (StackGroup) e.nextElement( );
			if ( sg.alUnitPositions != null )
			{
				for ( int i = 0; i < sg.alUnitPositions.size( ); i++ )
				{
					asu = (AxisSubUnit) sg.alUnitPositions.get( i );
					asu.reset( );
				}
			}
		}