Use the previous "select mode" dark toolbar style for Write mode

[richtabor]

Let's try adding an additional affordance to write mode to help you understand what "mode" you're in, writing or design, by leveraging the pre-existing styles for select mode. This way there's a clear visual affordance to indicate the difference in experiences.

Visual

Related #65298.

[hanneslsm]

I like the idea.
Another one would be leveraging bottom bar, that currently only holds the breadcrumps.
We could add the name of the mode in the bottom bar like in VIM. In VSCode it's even officially called status bar