The tracker module allows certain users to assign resolvers. This is fine. However, in some circumstances, it may be desirable to restrict the assignments more but allow certain users to claim the issues. By claiming I mean that a user can assign the issue to himself but nobody else.

This idea comes from other tracking programs. Even eTicket, a very basic general-purpose open-source help desk system, supports it. eTicket is actually quite similar, actually simpler in terms of functionality, to this tracker module.

http://www.eticketsupport.com/