Current behaviour with vertical tabs doesn't show "Close Tabs Below" when clicking on the last tab in a tree, even if other trees are below it. It doesn't show "Close Tabs Above" on the first child tab of any tree, even when there are other trees or branches (and the root tab itself) above it. It does show "Close Tabs Above" on the root of every tree except the first one, which makes sense, but I think it should also show on the first child tab.
I suggest that every tab except the actual current bottom-most tab of all trees shows "Close Tabs Below", and every tab except the top-most tab of all trees shows "Close Tabs Above", as I think this is more intuitive and would help with managing tabs.
A user would be able to easily close all tabs above or below a given tab. This already works in almost every case, except those outlined above, and these exceptions are unintuitive in a vertical tab setting.
