Hi Philippe,
This functionality is not supported as standard for the quick lookup dropdown list when inserting values used for lookup. While the lookup dialog screens offer more filtering options, the dropdown list is intended solely for quick value selection. You can always click the lookup action button to apply additional filters or retrieve more information to support your decision-making.
Implementing the behavior you're suggesting would require custom code changes, which are not part of the standard functionality—and it may not stop there. In your case, you want to exclude obsolete products, but other filters might also be relevant, such as inventory type or showing only available inventory (though backordering may still be desired). The key point is that no filtering is applied to the quick lookup, and different businesses may have varying requirements.
If I'm not mistaken, the code behind this is part of a general application layer, meaning the quick dropdown functionality is shared across multiple modules. While filtering out obsolete items might be useful in one module, another module may require access to those same items. Therefore, even with custom code, implementing such filters would require maintaining module-specific logic, which adds complexity and overhead.
