Don't forget, Opera has very huge user too... :)
Thank you for your feedback. Right now you can use a Todoist extension with every browser thanks to Todoist Anywhere. Please go to http://todoist.com/anywhere for detailed instructions.
Ever since version 15, Opera stopped supporting bookmarklets. When Opera 19 comes out, you can enable the bookmarks toolbar from the settings every time you want to use a bookmarklet. I see this as a less than ideal solution for current Opera users. Even a pinned tab or a speed dial is a better solution in my opinion.
But turns out, ever since Opera switched to the Chromium core, it's been supporting the Chromium extension model to some degree. You can just simply install Chrome extensions if you download them. And even better, some one made this:
Simply install that and install todoist from here:
You have to confirm the installation by clicking Ok in the notification bar that pops down, then install it from the extensions page that pops up. Works like a dream for me in Opera 19.
Even if I think it's worth it, I think this is a bit of a hassle if you're only doing it for the todoist extension. But any one, even my grandma could have uploaded the extension to the Opera extension library. Only basic computer usage skills needed. So could you just simply do that? I could even do it for you for free. Won't take me more than 10 minutes.