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
int startColumn = cellContent.getColumn( );
					int endColumn = cellContent.getColSpan( ) + startColumn;
					CellArea emptyCell = AreaFactory
							.createCellArea( cellContent );
					resolveBorderConflict( emptyCell );
					IStyle areaStyle = emptyCell.getStyle( );
					/*areaStyle.setProperty( IStyle.STYLE_BORDER_TOP_WIDTH,
							IStyle.NUMBER_0 );*/
					areaStyle.setProperty( IStyle.STYLE_PADDING_TOP, IStyle.NUMBER_0 );
					areaStyle.setProperty( IStyle.STYLE_MARGIN_TOP, IStyle.NUMBER_0 );
					emptyCell.setWidth( getCellWidth( startColumn, endColumn ) );
					emptyCell.setPosition( layoutInfo.getXPosition( i ), 0 );
					row.addArea( emptyCell );
				}
				
			}
		}
		
		
		if(height>0)
		{
			HashSet updated = new HashSet();
			for(int i=0; i<columnNumber; i++)
			{
				CellArea cell = row.getCell( start + i );
				if(cell==null || updated.contains(cell))
				{
					continue;
				}
				updated.add(cell);