I'd like to propose 2 things:
1. I see the 4 numbered icons as "what am I selecting?" (object, vertex, face, terrain) and 3 "manipulators". I propose the numbered ones be moved together, followed by (spacer?) the 3 manipulators.
2. I'd really like hotkeys for these, 1-4 would be ok for the selectors. but i don't know about the 3 manipulators? some software use g, s, r but i like being able to use wasd for movement.
so what do you all think?