In Session Monitor | Current Statement | Explain Plan, highlight the currently executing step in the plan. This information I believe can be had via V$SESSION_LONGOPS.
Right now there is a plan "cursor" that is yellow by default but it is just for working with plan rows (like hitting F4 to describe the object in the step).
If we could do some other highlight like marching ants (Photoshop style) or something else that would give us some clue as to WHERE in the plan Oracle is churning on.
Right now it's not easy to figure that out via the Long Ops tab because, yes, you know the object but if the object is used more than once in a query you don't know which one.
In the attachment I have mocked up a green rectangle around the "currently executing step". You could do better than my mockup but it's a start.
I realize this would be for long-running statements only and that's okay. Who cares what step we are in if the query takes 150ms? But if it is taking 150 seconds, now we start to care.