Cheers so what is happening on the secound level boxes etc
Nothing... rumour has it that there is deliberately space above to put in a second tier, should the club wish to apply for planning permission to expand - this picture shows the finished product and the 'space' where a second tier could go:

Also, rumour has it that two of the corners could be filled in, as per the diagram on the last page of this pdf booklet:
http://www.seagulls.co.uk/staticFiles/37/dd/0,,10433~122167,00.pdf