https://split-browser.pdfwork.com/
Split Browser Windows
split browserwindows
https://perldoc.perl.org/5.28.1/AutoSplit
AutoSplit - split a package for autoloading - Perldoc Browser
splitpackageautoloadingbrowser
https://forums.opera.com/topic/44626/split-screen-in-the-browser/5?lang=en-US
split screen in the browser | Opera forums
Sep 30, 2021 - @zan9822 Yes, by the time when Opera used something called Multiple Document Interface (MDI).
split screenthe browseropera forums