The back (left) button on the top right looks clickable after just launching the app even though clicking it has no effect. It correctly has no effect since no action would be suitable because no navigation has taken place yet, but then it should not look clickable.
Seeing it non-clickable helps me grasp where I am in terms of navigation. For example if I see the left button disabled I know I’m home at a glance. On the flipside, if the rest of the UI looks like I’m home but the button is not disabled I’m confused at to wethere I have gone “all the way back”.
It may be noteworthy that I’m navigating mostly by clicking with the mouse to go where I want (quite standard), and then when I’m done I go back up the navigation tree I have a mental model of in my head using my mouse’s back button.
Just a note on how to pull this off: there’s no easy way to know whether we’re at the bottom of the stack with just browser primitives. We’ll have to keep track of the history manually in our router code.