Bug 152560 PDF doesn't display bottom Border in inner group footer properly
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/layout/pdf/PDFTableLM.java
{
				String dropType = cellDesign.getDrop( );
				if ( dropType != null && !"none".equals( dropType ) ) 
				{
					rowSpan = createDropID( groupLevel, dropType );
				}
			}
		}
		for ( int i = cell.getColumn( ); i < cell.getColumn( )
				+ cell.getColSpan( ); i++ )
		{
			if ( currentRowContent[i] == null )
			{
				currentRowContent[i] = new CellWrapper( cell, currentRowID,
						rowSpan );
			}
		}
	}
	
	public boolean isCellVisible( ICellContent cell )
	{
		if ( cell == null )
		{
			return false;
		}
		return currentRowContent[cell.getColumn( )].cell == cell;
	}
	protected void createRoot( )
	{
		root = (ContainerArea) AreaFactory