Openerp 7.0 20130804-231043

I need an admin account to configure users and group. So I create an "Adminconf" account with the "Administrator/Access Rights".

BUT, this accout still has the rights to modified "Setting->Group->Adminstration/Setting->Edit->Users->Add" and upgrades himself with "Administrator/Setting" rights. Even more, he can create a new user and grant it with "Setting rights".

How can I avoid this? Or Is it a bug in openerp7?

In my real application : "Adminconf" account is used for configuring other users except "administrator". It has no rights to access "Administrator /Setting group" or give other users "Administrator/Setting rights".