Comment 10 for bug 528320

Now to answer other comments: in OpenERP rather than accepting false "cancel" actions on document that can't be cancelled (typically invoices and pickings), we currently provide wizards to create the reversed documents. For example you can use the return picking wizard on a picking, or the refund invoice wizard on an invoice.

As stock moves are usually less strict than invoices in legal terms, and often more error-prone (missing traceability info, packs, etc.), in v6 we will attempt to make the pickings/moves partially editable even after being processed, to be able fix these kinds of errors (except some main fields that won't be modifiable: products, quantities, locations, etc.). In terms of completely cancelling the document however, we still won't allow doing it, a reversed one must be created instead (and traceability will include the return accordingly)