Topics created by ichanath

I suppose you are right. In KDE (I have XFCE with Kwin) in Aliya Linux, that is based on Debian Stretch and in KDE Neon (Ubuntu), the menu is quite nice and I can have no border. In Ubuntu with Openbox (Nelum Openbox), also I can un-decorate. In Devuan (Nelum-Dev-1 Testing), it can also un-decorate. If the Ubuntu based distro has Gala Window Manager, it can't. Once there is no border, the minimize and maximize buttons go away. This doesn't happen in Windows 10. Maybe, the Opera devs take heed. I'm now using Opera Beta, for in a few days, it'd become 45 final.

Does any Opera dev reads comments here?

Some of them probably do. However, you should not expect them to answer any comments although they may do it eventually.

there's no use asking questions.

This place is mainly for users to talk about Opera and try to help each other with their issues.

Are they installed, or available?

Only one theme is installed at a time. The others are available.

I don't have an option to undecorate (permanently) in Ubuntu distros like ZORIN OS 11 and LINUX MINT, if I remember right Kubuntu didn't have it neither. I broke few Ubuntu distros installations trying to learn to hide titlebar in Opera similar as Chromium/Chrome has it (and also Firefox with addons like 'No caption' and 'Hide Caption Titlebar Plus')
I did this because Firefox seems to slow to me even on fast computer, Chrome has it's own disadvantages and other browsers don't have capability to add plugins or are not updated or similar...
So this leaves me with Opera-unfortunatelly it doesn't have a nice upper side because of the titlebar and this also wastes space; I am used to this being improved like in Chrome or Firefox.

There is a software COMPIZ which undecorates all windows in Ubuntu distro (Email client, file explorer, Opera and everything else), but then you cannot even minimize or exit/close the programs in a nice way which is even worse.

I read online that some of other Opera users want this feature too.
I would even be willing to make a small donation if this would be done.