@stefantrethan Thanks, that is good to know! However I have already got used to the new style, mainly because wider sidebar in 4K resolution is not a big deal. So I will stick to it for now. But thanks anyway!

Thanks, @thomasmca, I have already found a way to make it work again. Apparently it is now dependent on the visibility of the side panel, so in the end the solution was just to turn on this panel and voila, it is there. It is a bit different though - it is wider (and not adjustable to be less wide) and it takes the whole height which means it pushed the address bar and back/forward buttons to the side, but otherwise it works as before. It might take some time to get used to these changes, but it is still a very good solution for all of us, who like to use their widescreen monitors to maximum efficiency.

It worked well until recently, but it suddenly stopped. The icon in upper toolbar is unclickable and sidebar does not appear at all. Reinstalling and fiddling with settings did not help. My current Opera version is 66.0.3515.44.