Could also be interesting for product comparisons, shopping or watching videos in one half while doing something else in the other half of the screen.

A quick check on the Mozilla Firefox website did not bring up the desired Firefox extension that would copy that behavior. The extensions that I found where either outdated or crashing my Firefox. That’s when I decided to ask you if you knew of an extension that would mimic the behavior of the Dual View plugin.

All I need is a way to display two websites in one Firefox windows next to each other instead of in their separate tabs. I could open two instances of Firefox and run them next to each other but I would prefer an extension that would enable the functionality so that only one instance of Firefox needs to be running.

So let me know if you are using or remember a Firefox extension that does that. Opera users could also weight in and let me know if Opera supports such a feature as well.