I love Opera and in my day-to-day work I use it a lot. I very, very often use look-ups for key words or phrases in a page with ctl+f, as that saves me tons of time, for code, for documents - webpages/pdfs. The thing is that what I see that Opera delivers is just a basic look-up but there are no options to constrain the word look-up to be by matching by case or whole words (like Mozilla allows for instance), by regex. Further, to some reason it does not find words as well as Mozilla in pdfs in my observation, too.
I would be happy to see a bit more expanded version of the word look-up functionality of the browser.
Keep the great work up!
All the best,