Chromium has an option to toggle the native title bar in the context menu of the tabs area. It would be nice to have this on opera as well. I have made a rule in kwin to strip the title bar, but now I only have a "close" button, while "minimize" and "maximize" are missing.

So, it'd be nice if we had a toggle option natively instead of having to use a WM specific workaround.
It'd be also nice to have a "minimize" and "maximize" buttons, not only "close"

[Moved to Opera for *nix]

This should be doable from the Opera UI, not requiring installing another software and editing the files manually. Besides, what happens when Opera decides to reload the thumbnails? Right, back to editing everything again...

...it's wasting space and I can't seem to find how to disable it. I don't edit my speed dials often, so I have no use for this tile. If I suddenly decide to add a new speed dial, I'll just right-click on a site and do so. Please consider allowing to hide it.

Opera seems to prefer using adobe flash player on youtube for me. If I disable it via about://plugins, youtube loads the HTML5 player. I would like opera to behave like chromium and prefer HTML5 over flash - mostly because flash doesn't offer the 60fps option. Is there a way to do that? I can't seem to see any related setting on youtube itself.

Chromium has an option to toggle the native title bar in the context menu of the tabs area. It would be nice to have this on opera as well. I have made a rule in kwin to strip the title bar, but now I only have a "close" button, while "minimize" and "maximize" are missing.

So, it'd be nice if we had a toggle option natively instead of having to use a WM specific workaround.
It'd be also nice to have a "minimize" and "maximize" buttons, not only "close"

[Moved to Opera for *nix]

I dislike this idea to be honest. Because using tab in the address bar has always served another purpose: moving the focus away from the address bar onto other areas. This isn't only something within Opera but most other browsers (FF, MSIE) follow this same principle. So I can't help wonder if this wouldn't make things a lot more confusing.

Not at all. The only instance where TAB would not jump away if you are switching between website address and search mode (which involves you typing in the keyword in the first place). In that sense, it is shifting focus elsewhere - from the address bar to the search bar. Only that their position is the same.

Besides; alt-left and alt-right already allow for this behaviour (selecting other search icons).

I wasn't asking for TAB to switch between search engines, but thanks for that tip, this makes it faster than Chromium.

I'm not sure what you mean. You can switch the search engine without retyping in chromium as well, for example type a->tab/space->chromium shows search engine for 'a'-> type your request -> jump to start of request -> press backspace -> chromium exits search mode -> type 'b' for another search engine -> tab/space -> chromium will search for the query using search 'b' (no need to retype, just like opera)

What I want is to be able to use TAB to switch to search mode on keyword, not only space. Plus, that it adds engines automatically when it finds them, maybe as an option.

And visually, I think this is cleaner than this

In chromium, when you search on a website, it automatically creates a search engine with the website's name. This is of course still customizable, but what I really want to have is the way switching to a search engine works.

Currently, you type in the search keyword followed by space. I'd prefer to have an option for the keyword to be followed by TAB key to switch to search mode instead. Currently, it just jumps away from the address field.

Basically:

enter a few letters of the address 
   -> completion list shows up 
       -> select website from the list 
           -> TAB -> search
           -> ENTER -> go to website

The new auto-generated thumbnails make sense most of the time, but sometimes they don't. For example, any forum hosted on a free board, like zetaboards shows something like z11.zetaboards.com. This doesn't have anything to do with what is actually bookmarked.

Setting my own picture should be an alternative.

What's the difference?
Read the second part of the sentence you quoted
Also, user-friendliness.

This should be doable from the Opera UI, not requiring installing another software and editing the files manually. Besides, what happens when Opera decides to reload the thumbnails? Right, back to editing everything again...