Here a few explorations on how to visualize the top toolbar when active, adapting G2 styles.
Some alternatives permit the top bar to remain clean to potentially absorb more functionality and stay focused.

A (Absorbed by top bar as is today)

B (Creating a second level)

C (Aligned with the top bar UI, 2 options)

D (Horizontal position fixed pointing to the block content area)

E (Centered)

Relevant to:
#20575
#6047
#7485
#3735