Open multiple urlbar, bookmarks menu, etc urls in background and leave the menu open

[mzso]

This feature I constantly miss. Just middle click multiple urlbar or menu items and have them open in a background tab. No fuss, very practical. But now at most it's possible ctrl+shift LMB to open urls in the background, but the urlbar still resets, and it's not convenient to press ctrl+shift or shift middle click anyway.

Via addons it used to be possible to get urlbar results to open in background tabs for middle clicks, and also for the results to remain open.
In particular I remember Stay-Open Menu allowing me to open multiple urlbar or other menu items to be opened in the background conveniently.
But that XUL addon is gone now. But the inconvenience remains, constantly. It's such a nuisance to re-do searches in the urlbar constantly or reopen menus several times.

The browser of course still doesn't provide any solutions. At one time it seemed the feature might get into Firefox: https://bugzilla.mozilla.org/show_bug.cgi?id=1753863 But that effort died, because Mozilla people in charge didn't give a crap to review and supervise it, even though the external dev was willing to implement it...

So customization is the only hope. Did anyone has or saw such an userchrome JS script? Or is interested in such feature?