Tiny macOS utility that mirrors an external monitor in a resizable window

Some screenshots or something would help.

The video that is on the site, but buried, doesn't seem to show anything.

The video shows exactly what the tool does… far from buried, it’s explicitly labeled “what”.

Neat!

This would be cool as a menu bar application that shows up when it detects an external display, sort of like a rear-view mirror for my Mac. I wonder if it would be possible to move things around inside it with the accessibility APIs that window managers use.

Can it also just be an extended second display instead of just mirroring? Would be cool

Use a dummy HDMI adapter?

seems like an app like BetterDisplay would be more suited to that

As in creating a virtual display and mirroring that into a window (instead of mirroring an existing display)? There was an HN post[0] about a piece of software called DeskPad about 8 months ago that does exactly that.

BetterDisplay can also do both, as well as a truckload of other things (some free, some paid).

[0]: https://news.ycombinator.com/item?id=41800602

Cool, thanks!