Hi everyone. Long-time Opera user here, tried the rest, settled for the best!
I've done a lot of searching today to fix one of my major caveats with Opera (and all other browsers as well), and that is disabling the backspace key to act as a 'back' navigational button. This can be extremely frustrating for those who've just completed a page with tons of field forms, only to accidentally nix the 'backspace' button and have it all destroyed.
Apparently, there are quite simple solutions for some of the other browsers out there. I didn't find any easy fix for Opera in particular, but after some searching, I found the fix. Hoping this will help some lost, frustrated soul out there in the interweb abyss...
First, simply download & install a Chrome-style addon emulator, made for Opera, here: https://addons.opera.com/en/extensions/details/download-chrome-extension-9/?display=en
Restart Opera, then head over to https://chrome.google.com/webstore/detail/backstop/pidcjgldchekcoolelhbjfbnccjkckfj?hl=en-GB to download 'BackStop', the acual Chrome app that fixes this issue.
Restart again, and voila, problem solved. Hope this helps, and Devs, keep up the great work!!! Loving your browser.