Custom transaction for VF02

Hi All,

I have a Z transaction for VF02 where in the user using it have access only for changing the text fields inside the transaction and all the other fields comes as output only.

Now i need to modifie this transaction such that only when the user is creating a new invoice he should be able to change the texts, while entering in the change mode ( normal) the transaction should behave as a display only.

Also on completion the control should return to the Z transaction rahter than goin to VF02 ( this is happening now and few users are getting a no authorization message).

Thanks in advance

Derek