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
tableLM = getTableLayoutManager( );
		cellContent = (ICellContent) content;
		
		
		int startColumn = cellContent.getColumn( );
		int endColumn = startColumn + cellContent.getColSpan( );
		columnWidth = tableLM.getCellWidth( startColumn, endColumn );
	}
	protected void createRoot( )
	{
		if(!isFirst)
		{
			int startColumn = cellContent.getColumn( );
			int endColumn = startColumn + cellContent.getColSpan( );
			columnWidth = tableLM.getCellWidth( startColumn, endColumn );
		}
		if(root==null)
		{
			
			CellArea cell = AreaFactory.createCellArea( cellContent );
			cell.setRowSpan( tableLM.getRowSpan( cellContent ) );
			root = cell;
			
			
			if ( !isFirst )
			{
				IStyle areaStyle = root.getStyle( );
				/*areaStyle.setProperty( IStyle.STYLE_BORDER_TOP_WIDTH,
						IStyle.NUMBER_0 );*/
				areaStyle.setProperty( IStyle.STYLE_PADDING_TOP, IStyle.NUMBER_0 );