Let pinned vertical tabs be stacked vertically, not only horizontally

[0badc0d3]

For some unknown reason, pinned vertical tabs get stacked horizontally only, packed as tightly as possible within the current side bar width.
I can get them stacked vertically by reducing the side bar width, thus reducing all tabs to just the icon.
There is plenty of room for a couple dozen tabs in that side bar, and users can decide whether display just the icon or also (a part of) the title/URL.
A similar feature can be seen in Vivaldi browser.

[Jon]

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