If it is an extension for Chrome, then there are extensions for Opera that will let you add Chrome extensions. If you can't do it in Chrome, then it isn't possible in Opera.
hi, I'm the author of it
what do you mean ? rendering bug or ...
your custom sessions or auto-sessions?
if you can post screen shot, it would be helpful
I was searching how to that by myself and found no solution apart from grabbing page canvas and saving that, but tab must be activated to do it, so it's useless.
yea, there is no proper way to grab background (never active) tabs screenshot. We need access to already implemented tab previews 🙂
I'm asking myself why that happens... In chrome there was no way to tell since all extensions where just in a popup (or a separate popup window), so active window was usually the current one, so maybe it's a recent fix in chromium 46, but I can't tell if that is the case. Or maybe just a bug in Opera. 😕
As mentioned above, warning of this is already mentioned in the permissions. Please check the "permissions" category, both on the addons page as well as well as the extensions management page in the browser itself.