In the v0.16 Insider version, the sidebar is merged when window frame style is set to hidden. This gets rid of the top bar but makes space for 3 fewer tabs in the sidebar. The sidebar tab row could be placed under the top bar to get the best of both worlds.
The “Obsidian frame” works as the old version, but that takes up space in the whole window.
So instead of this in Obsidian mode:
And this in hidden frame:
We could have this in hidden frame or another option:
