Let me know if this has been discussed or if I’m dense, but it seem as if there isn’t a way to go back to the previous page in Side View.
The Side View feature is super helpful but navigation is seriously stunted for me when this isn’t included. If anyone knows anything I don’t, let me in on it.
I don’t think there is. I don’t think they intend for you to use it to browse, but to open a page (for example, video or audio stream) and just leave it until you’re done, and open a new side view if you need something else. It’s extremely limited, especially when compared to the Tile Tabs extension that isn’t available in quantum.
This might be supported once the <iframe> controls can be added back, which is currently blocked on bug 1318532: