Bug 188843 NPE throws out when preview sample report in xls[1203]
engine/org.eclipse.birt.report.engine.emitter.prototype.excel/src/org/eclipse/birt/report/engine/emitter/excel/StyleEngine.java
int start = ( (Integer) pos.peek( ) ).intValue( );
				applyContainerTopBorder( span, start );
				style2top.put( style, Boolean.FALSE );
			}	
		}
	}
	public StyleEntry createHorizionStyle( int pos )
	{
		Span span = (Span) spans.peek( );
		StyleEntry cEntry = (StyleEntry) styles.peek( );
		StyleEntry entry = StyleBuilder.createEmptyStyleEntry( );
		StyleBuilder.mergeInheritableProp( cEntry, entry );
		if ( pos == span.getCol( ) )
		{
			StyleBuilder.applyLeftBorder( cEntry, entry );
		}
		if ( pos == span.getCol( ) + span.getColSpan( ) )
		{
			StyleBuilder.applyRightBorder( cEntry, entry );
		}
		return entry;
	}
	public void calculateBottomStyles( )
	{
		Span span = (Span) spans.pop( );
		StyleEntry entry = (StyleEntry) styles.pop( );
		int col = span.getCol( );
		int cp = dataMap.getListSize( col ) - 1;
		for ( int i = 0; i < span.getColSpan( ) + 1; i++ )
		{