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/PDFBlockStackingLM.java
areaStyle.setProperty( IStyle.STYLE_BORDER_BOTTOM_WIDTH,
					IStyle.NUMBER_0 );
			areaStyle.setProperty( IStyle.STYLE_PADDING_BOTTOM,
					IStyle.NUMBER_0 );
			areaStyle.setProperty( IStyle.STYLE_MARGIN_BOTTOM, IStyle.NUMBER_0 );
		}
		
		
		int height = getCurrentBP( )
				+ getOffsetY( )
				+ getDimensionValue( areaStyle
						.getProperty( StyleConstants.STYLE_PADDING_BOTTOM ) )
				+ getDimensionValue( areaStyle
						.getProperty( StyleConstants.STYLE_BORDER_BOTTOM_WIDTH ) );
		if ( isFirst && isLast )
		{
			calculateSpecifiedHeight( );
			if ( specifiedHeight > height )
			{
				CSSValue verticalAlign = areaStyle
						.getProperty( IStyle.STYLE_VERTICAL_ALIGN );
				if ( IStyle.BOTTOM_VALUE.equals( verticalAlign )
						|| IStyle.MIDDLE_VALUE.equals( verticalAlign ) )
				{
					int offset = specifiedHeight - height;
					if ( IStyle.BOTTOM_VALUE.equals( verticalAlign ) )
					{
						Iterator iter = root.getChildren( );