Yes, I see that on Windows categorization, but was the unique post about that.
I am a new Opera's user (31.0). But the protocol manager missing makes me sick. I try for hours to change the simple application attached with a specific protocol 'tg' (telegram) on my Opera at my Linux and nothing... I search crazily for some text entry to change on sources ~/.config/opera, but it's hard. I don't find any entry of "(tg) | (telegram)" for do this changes easily human, so much binaries...
Don't have a 'human' method to change my protocol's apps default? That it's really annoying.