I have now for a few hours run four sessions of Reactor on each their virtual desktop. I use the Opera browser and they all run continuously in parallel. The browser has version no. 72.0.3815.378. If Opera also gets into the same problems as Edge and Chrome in the future, I can see that at http://www.opera.com/download and at the very bottom of the page there is an archived with former versions of Opera, so it should be possible to find one previous version which hopefully can run multiple Reactor’s at the same time.