I need something like this diagram:
Navigate in Category A/B/C (Area1) -> on the left panel show a Search Module -> if the user search a term from that module i invoke Mage Catalogsearch module with a new parameter (eg: /catalogsearch/result/?q=term1&a=area1) and the result of the search have to be only from that categories.
If i search the term from the main search form (the top one) i see result from every category.
Is this possible? I've to extend/overwrite something? Any hint or suggestion?