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/cache/TableAreaLayout.java
{
			return;
		}
		Row row = (Row)rows.getCurrent( );
		assert(row!=null);
		int rowHeight = row.getArea( ).getHeight( );
		int height = rowHeight;
		boolean needResolve = false;
		
		for(int i=0; i<columnNumber; i++)
		{
			CellArea cell = row.getCell( start + i );
			if(cell!=null && cell.getRowSpan( )==dropValue)
			{
				height = Math.max( height, cell.getHeight( ) );
				needResolve = true;
			}
		}
		
		if(needResolve)
		{
			HashSet dropCells = new HashSet();
			int delta = height - rowHeight;
			for(int i=0; i<columnNumber; i++)
			{
				CellArea cell = row.getCell( start + i );
				if(cell==null)
				{
					continue;
				}