Sessions, it's not rocket science!
You're right, its not, thats why theres already extensions that add this functionality to Opera.
When searching I only found one, TabHamster, which does not work. It doesn't save the sessions correctly, so session comes up with zero tabs in most cases, and when it has some tabs saved it doesn't restore them correctly either, just restoring N blank tabs.
Though, this is basic stuff that should be in Opera itself. They have about 90% of the code there already, if not more.
Type opera://history/ into your address bar. Hopefully that will help you dig up some of the links you lost.
Yeah they're in my history, along with 500 or so unrelated links from the same time period...
This OP didn't even bother to list his Opera or OS version.
Opera version fair enough, clearly I'm on Opera Next otherwise I wouldn't be complaining about this, but to be specific 26.0.1656.60. But OS version... really? You saying they selectively showing some session related menu points based on Windows version? If so, which version of Windows has them?