You need to buy one of these (see link below), I think. My inner window has just fallen out too and I'm just about to buy this to see if this will do the job
http://www.appliancespareswarehouse.co.uk/product/default.aspx?act=s&part=QUAGSK113&shop=NEFF&gclid=CPSisqWaipsCFVIB4wodukQzpQ
Jon
June 2009