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
areaStyle.setProperty( IStyle.STYLE_MARGIN_TOP, IStyle.NUMBER_0 );
			}
		}
		tableLM.resolveBorderConflict( (CellArea)root );
		root.setWidth( columnWidth );
	}
	protected void initialize( )
	{
		boolean isNewArea = (root==null);
		createRoot( );
		if(isNewArea)
		{
			IStyle areaStyle = root.getStyle( );
			removeMargin( areaStyle );
			validateBoxProperty( root.getStyle( ), columnWidth, context.getMaxHeight( ) );
			setOffsetX( root.getContentX( ) );
			setOffsetY(root.getContentY( ));
			if ( isFirst )
			{
				isFirst = false;
			}
			setCurrentBP( 0 );
			setCurrentIP( 0 );
		}
		maxAvaWidth = root.getContentWidth( );
		root.setAllocatedHeight( parent.getCurrentMaxContentHeight( ));
		maxAvaHeight = root.getContentHeight( );
	}
	protected void closeLayout( )
	{