Captive networks is rather annoying when I'm travelling and have a multi-tab preloaded session running (or closed, not that it matters). Hotel, public transport, airport and airport networks that I've come across usually do something like this.
As Opera is my standard browser the captive networks will reload all existing tabs to the login page for that network. I don't think this applies to HTTPS-sites as they will throw off the reload and therefore keep the URL in the tab.
What I'm hoping for is some way for Opera to detect that it is connected to a captive network and open a new tab/window for login, rather than reloading every existing tab.
I do realize this might be an OS-issue as OS X has a built in Captive Network Assistant that opens a new window in Safari for login, but as far as I can tell Windows 10 (Bootcamp, main OS) does not have this feature.