Recently, I've started using the Atom Editor, and I wanted similar functionality to quickly select multiple lines of text and do the same action on all of them.
Apparently, there is some built-in multi-cursor functionality in Atom, but it's mouse-only. You have to Ctrl-Click each place you want to put a cursor.
Luckily, Atom is extendable with open source packages, and I was able to find multi-cursor, which did almost everything I wanted.
The original directions for updating the keymap were incorrect, so it didn't function for me until I updated it to this.
# Expand current cursor
Warning: Ctrl-Alt-(Up/Down/Left/Right) can be the default hotkeys of changing your screen's orientation in Windows, so unless you want to do that, update the atom keybinding to something else or remove those hotkeys from the graphics settings.