This solution was provided by Sgunhous

Excellent solution, though for the wrong problem :-p ... the issue is to change the default search engine (i.e. w/o using a prefix) away from Google.

But thanks anyway, at least this makes using Google a bit more bearable as I'm usually searching in English but until now Opera was so "helpful" to force me to my native language.

+1, this is currently my reason to stick with chrome.

If it's possible in the original, it's imho highly dubious Opera removed it actively and the malware protection reason doesn't seem quite conclusive for me. It rather sounds like a contract with Google, or there at least would be some hidden power user option to change the default search engine (some .js in a protected directory or a shortcut, I suggest UP-UP-DOWN-DOWN-LEFT-LEFT-RIGHT-RIGHT-UP-UP-DOWN-DOWN-LEFT-LEFT-RIGHT-RIGHT).

Sadly, to me this is an indication that opera has moved away from the "users first" spirit to the "take it or leave it" way after being forced against the wall by the competition :-\

I'd just like to add my 2ct about another change from chrome to opera:

With every minor update, the updater exe changes and I have to ack it anew to reach the network. I'm using an application level firewall that uses rules for each exe. Using a generic updater process like google does would solve this hassle.

I just tried to switch from chrome to opera, hoping that it skips some of the more dubious google choices like forcing on the desktop notification in the newer builds.

However, the crippled search engine functionality is a show stopper I'm sorry to say. I'm not ranting, I respect opera is using google's engine and probably has to contribute something back like the hardcoded "g" bang and the prevention of the removal of the google engine even after deleting "default_partner_content.json".

But for crying out loud, not being able to set my own engine to default is so annoying I'm going right back to chrome. I hope the "temporary" situation doesn't last longer than the half year by now, I don't know if you realize that forcing this choice on users might hurt opera more than you realize and a re-negotiation with google might be feasible.

Thanks for keeping opera alive anyway, maybe I'll have another look when this is resolved.

The option to set a custom search engine as default was (temporarily) removed to combat malware overriding user settings and directing all searches to malicious third-party sites. Its an unfortunate situation.