Nobody has any idea what to do? And why such a problem appears?
I thought that perhaps down scaled window is too big, but really small window behaves in the same way.

Is there any way to use /force-device-scale-factor without Opera window snapped to the top of the screen each time I open the browser?

Because of the problems with my eyesight I'm using big, already 32" display and custom scaling factor in Windows 10 (FHD + 125%). Unfortunately what's good for many applications or games doesn't work well with Opera Browser - it's UI is huge. websites also could be "smaller" and of course I can use custom zoom level for them, but for the UI I can't (that's not Vivaldi :()

/force-device-scale-factor parameter works great but every time I open my browser it loses the last window state. Not it's size or horizontal position, but the vertical one. Window is always placed close to the upper edge of the screen... no matter of the window size.

Can I do something with It?
Using window size and position parameters doesn't help!

Ee... OK, it Seems that it was my fault... Is there any way to use /force-device-scale-factor without windows snapped to the top of the screen each time I open Opera?...

Jesus f....g Christ, when will you fix that irritating bug with loosing last window state - size and position! Do I really have to downgrade to Opera 68?!

@aleksod: More beautiful? Good joke. that new floating panels are awful (as well as the tabs bar, quick settings panel, new downloads page)... Thank God there are flags to disable them...

And why I say so? Because there was no Bookmarks panel for so many years, that I've used to use Chrome Extensions (Neater Bookmarks or, currently, Minimal Bookmarks Tree) which I consider a lot better (size and shortcuts settings) and to treat side panel buton as a shortcut to the "big" b\Bookmarks Manager. Actually that become a really convenient and to be honest i don't want to lose that because after five or six years since Opera Blink release their authors finally decided that bookmarks on the side are good idea.

And yes, I don't like the history panel too.

BTW why all these graphic elements are so huge, so heavy? Even though almost everything is plain white it's also so big, with so much free spaces, so much weight... Huge overwhelming tabs/title bar, huge heavy floating panels, huge quick settings panel with huge colour switches and a lot of empty spaces... It's 2019 and I see that UI is still designed for the only one right resolution and one specific DPI. What about people who are using different combinations than FHD + 100 DPI or 4k + 150/200 DPI? UI in these cases really doesn't look good. It becomes wore and worse with every single update.

@temkem: Good to know, but we need a switch in Opera Settings, because flags like to vanish...

Can we disable that floating bookmarks panel in order to open bookmarks site directly from the sidebar?!

Yea, maybe, but I wonder why they are here. When they are created, when I change preferences? I don't do it so often

Can anyone explain me what these files are for? I've already found 91 Preferences~xxxxxx.TMP and about 30 TransportSecurity~xxx.TMP in my prodfile's directory...