RE: How to revert the modern look of speed dial thumbnails?
Yes, first with Opera 31, all of your thumbnails are changed to icons. I had tons of them. Then, it gives you the solace of manually jumping through all of those hoops, changing them back. And what happens with the next update? Will we have more of the same-- thumbnails changed to icons, with an option to change them back slowly, arduously, one at a time. I'm sympathetic to concern of @asl4u.
Also in an earlier version, the speed dial page had dark borders, and was, in my view, much nicer. Opera preserved it as an option for a number of updates at Opera:Flags. Suddenly the ability to use the dark borders was taken away in Opera 31, without an Opera:flags option to preserve the look. Would it have been so terrible to continue giving us this aesthetic option. Now we're stuck with the white borders. No choice! These white borders are more jarring to me, and don't look as good with the Themes I've selected for my Speed Dial as the darker borders.
I'm fed up with this forced updates, where Opera messes up what was gold, and makes it dross. And particularly with changing all of my thumbnails to icons. Of course, I can change it back -- one at a time. I don't have the time for this, or the inclination to do it, given the "shoved down your throat" white borders, and how Opera can knock everything out (thumbnails back to icons) in the next update. That seems to be the pattern.
I've been using the FVD Speed Dial with Opera and I like it better. You can set up multiple pages. The thumbnails look great. You can't do a folder of items for a thumbnails position, but with multiple pages (give each page, if you want, its own title/subject area) (not available in the Opera speed dial), you don't need to have the folders. Personally, I think it looks a lot better than the Opera dial. Also, the Opera Speed Dial, when you have a lot in it, loads slowly. This seems faster. In case anyone is unhappy with what Opera has done to its once great Speed Dial, but still wants to use Opera, here's the extension link.