many2one tree view custom search design issue : any advice ?

Hi there, new to openerp, I'm developping my first module :) So far, basic views and object declaration are ok. Let's move to more advanced stuff. I have an object A with a column like 'account_move_line_id': fields.many2one('account.move.line', 'Account Move Line'), I've got a form that look like linxo.transaction.formlinxo.transactionform

The goal is to perform a search for account.move.line, using criteria such as : - account.move.line amount close to object A amount - account.move.line amount around object A date The user will then pick from that list the correct account.move.line to associated to object A. I'm struggling with the road to take : - Custom widget and precise search (something like the default widget search more option) - Dynamically update domain to perform correct search in basic widget - Create a popup view not related to any model, perform search and take return of the popup to fix account_move_line_id (my favorite, but dont know where to start) Any pointers would be appreciated :)