Check if monitor is off

[quipuoiscriverciquellochevuoi at barda.cjb.net]

Hi X gurus,

Is it possible (theoretically or with an API) to check if a monitor is powered down by ITS power switch (not by DPMS) or switched to a video source that is not the video card, WITHOUT using DDC?

Until opposite evidence I think is theoretically impossible.

For now I am able to detect only if the VGA cable is disconnected.

Many thanks,
Antonio