I saw this post by Raymond Chen: https://stackoverflow.com/a/12865402/257299

The title says it all: Is it possible to program a custom dialog/pop-up for Alt+Tab switcher on Win 10?

Example: Can I trap EVENT_SYSTEM_SWITCHSTART, then show my custom Alt+Tab dialog with highest Z-Order? To be clear, I know this could be a security issue. Please assume the user local admin access.

Why? I want to program a replacement for the Win 10 "classic" Alt+Tab dialog that allows me to use the arrow keys. On Win 7, it was possible to do a key sequence like this: Alt+Tab (hold), the dialog would pop-up, then arrow keys would allow you to move left/right/up/down. After release Alt+Tab, the window focus would change. Very convenient! For me, the default Win 10 Alt+Tab dialog is awful, but the "classic" mode only needs a minor tweak.

Finally, I have Google'd like crazy before I asked this question. I cannot find anything.