Good brainwaves, 4wd, that can all be explored.

Anyway, Image Mirror' author, in the very same day I contacted him, implemented my suggestion: I tested it and replied (it was ok), and in the morning I had a mail announcing that on the website a new fresh release of the software was available. Fantastic.

From my tests, it seems to work very well (I still need to investigate on some problems, but I don't know if they're related to Image Mirror).

Unfortunately, there's no way to avoid the need of two screens, because Image Mirror can only flip a rectangular area that is actually shown somewhere in the desktop.

Making a software capable of just flipping the screen, in Windows, seems to be a very challenging task, if possible.

At the moment, I think Image Mirror is the best solution - of course let me know here if some better solution is found.

Ok, tests done (Windows XP) - here's the report.
Thank you very much, 4wd: you're an amazing software discoverer!

Mirrorimage seems slow, or anyway not fast enough on my PC for painting usage.

Image Mirror is great for this usage, in extended desktop setup with two monitors: I put the Image Mirror in the second monitor, and the painting app in the first one, choose the right refresh rate, and I get a fast enough mirrored view of what I'm painting.

Still, I'm interested in other findings, both for avoiding the necessity of a second monitor, and to obtain faster responsiveness, i.e. maybe something tailored to painting usage could monitor and update *fast* only a small area (around where the pointer is detected), and slow the rest of the flipped region. In fact, for 90% of the time, painting is about moving the pointer and leaving a trail near there ;)

No, that wouldn't work.
It's for painting with my graphic tablet under a glass-like surface positioned with a 45 degrees inclination next to a 90 degrees rotated monitor.
The virtual image of the lcd screen lays on the graphic tablet, but the real display should be flipped horizontally in order to see it correctly in the virtual image, and to match the movements of the pen on the tablet.

EDIT: there was no link to Image Mirror while I was writing. I'll look at it.