A visual interace is based on visual patterns. Accepting bounded data into unbounded gizmos is an important source of user dissatisfaction. All idioms must be learned. Good idioms only need to be learned once. Allow input wherever you output.
Any command is a working set candidate.
Ask forgiveness, not permission. Audit, don't edit. Consistency is not necessarily a virtue. Directly offer enough information for the user to avoid mistakes. Disks and files make users crazy.