Bug 178519 Problems in multi-rows header
Please see the attachments.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/layout/pdf/PDFCellLM.java
implements
			IBlockStackingLayoutManager
{
	/**
	 * table layout manager of current cell
	 */
	protected PDFTableLM tableLM;
	protected int columnWidth = 0;
	/**
	 * cell content
	 */
	private ICellContent cellContent;
	public PDFCellLM( PDFLayoutEngineContext context, PDFStackingLM parent,
			IContent content, IReportItemExecutor executor )
	{
		super( context, parent, content, executor );
		assert ( parent != null );