Add a Purchase Order status field and workflow

Having the ability to raise Purchase Orders is great (other SAAS solutions fall short in this area).

But I have a suggestion to further improve it.

Problem:
No way to distinguish between draft POs, sent POs, POs converted to bills, unwanted POs.

Solution:
Add a status field to POs (similar to bills).
The POs could then be progressed along a workflow from

Draft
Approved (or sent)
Converted to Bill
Inactive (or archived)

They could be presented on filtered tabs including the above statuses and All.

This way it would be possible to filter the POs according to their status
Draft ones that you are just preparing
Ones saved and sent to your supplier but awaiting delivery of the product/service
Ones that have been promoted to purchase invoices / bills
And ones that never got billed or sent and you want to archive out of the way.

That would be awesome!