Ctrl-Alt-Del, from the old NT days, was a Secure Attention Sequence, theoretically not interceptable short of a kernel driver, and took you to a separate deskto

Ctrl-Alt-Del, from the old NT days, was a Secure Attention Sequence, theoretically not interceptable short of a kernel driver, and took you to a separate desktop. NT supported separate desktops, but they're not like virtual monitors you see today; they're more like separate virtual ttys in the Linux console sense, entirely separate desktops with wholly detached window environments running on them. That's where the lock screen lived, and where Ctrl-Alt-Del took you to. Windows 7 probably changed that somewhat. I know the lock screen in Windows 10 is super buggy wrt customisation.