This is why Microsoft developed the Office ribbon – a tabbed set of toolbars.
It was very cleverly researched and designed by Jensen Harris' team:
https://jensenharris.com/home/ribbon
This is why you should be careful about what you put in your Sidebar-portion of your app's Toolbar and why you should give your Sidebar a suitable minimum width.
In Tower, if your Sidebar is too narrow, the button above it (which is an important navigation switch), gets moved into an overflow menu way on the right-side of the window.
They could easily fix this but the problem exists because its a new possible problem because of full-height sidebars.
