I decided to reinstall it. Strangely , I thought, there is still history even though I uninstalled it. Same problem cleared cache, same problem. Decided to follow the news feeds which go to Widgets magazine, something like ldsk.opera-mini.net; I'm on my computer so can't remember the address exactly. So looks like the actual culprit of this annoying popup is operamini itself. I have newsfeed turned off in settings, so this is something separate.