Feature request: flip horizontal (mirror image)

[ferfey]

I've been looking for a tool that will flip the orientation (horizontal) of my screen so that it can be read in a mirror. The idea is the Macbook/Modbook's screen will be sent to an ipad running Air Display 3 that is sitting in a telepromter similar to this. @CdLbB or @mscuthbert would something like this be trivial?

[mscuthbert]

I think it'd be a major change in the OS. If the macOS doesn't support it natively then it's not something that the rotation software can access.

[mscuthbert]

If you'd be willing to have only a window of a webpage be mirrored, I think it'd be pretty easy to do that.