It's good :)

а не сливается ли с фоном?

у меня на Windows 10 работает. у вас какая ОС и какая версия firefox?

What is you OS?

have no idea. I tried to turn off auto update of dials in Opera. And it works. Take a look at dials that are refreshing. Right click on them and check if Autoupdate is turned on or off.
If it's turned on, try turn off auto update in settings and check dials again. if they are still auto refresing, try to turn off auto update in dial directly and see what happens

I tried to do the same in opera. And focus there is still in my main window, while background updating is going.

It's not a bug actually. It's how WebExt version of Speed Dial. As Chrome user I got used to it. Now Firefox is going to support only WebExt versions of addons. Opera works on the same technology.

It's background updating of dials pictures. You can disable it in Settings

Also there is no account switching option. Only 1 account at a time

I guess this option can help you in your case

All dials and bookmarks are kept in browser even after logout.