Opera needs a confirm exit dialogue
This feature has been requested by Windows users for years
https://forums.opera.com/topic/13981/warn-before-closing-all-tabs
https://forums.opera.com/topic/20045/is-there-an-option-for-warning-before-closing-multiple-tabs/5
https://forums.opera.com/topic/10009/is-there-really-no-more-confirm-exit

Every other browser either has this feature built in, or it can be rigged up with an extension. The chrome extensions that can be added after the transferable extension (https://addons.opera.com/en/extensions/details/install-chrome-extensions/) do not work.
Apparently, Mac users have this option: http://help.opera.com/Mac/12.00/en/exit.html
If other browsers can do it, and if your own browser for Apple can do it, I do not understand why you cannot do this for Windows users. This is literally the only thing keeping me from using Opera as a default browser, in all other respects this is the best browser I've used.
It is such a basic, but vital, function. If there is some reason it cannot be done, please explain it.*