At the moment the Sidebar can show vertical tabs OR bookmarks OR your reading list. When you've not got many tabs open this results in a lot of empty space. Please make it possible for us to stack these features vertically in the sidebar instead of being forced to toggle between them.
The existing selection menu could be changed to allow us to tick multiple items, instead of just one.
This would make the sidebar much more useful and worth having open for those of us who don't tend to have many tabs open, but like the vertical tabs implementation. It would reduce the number of clicks needed, one of which is on a particularly tiny UI element.