Thanks jmaebe,
This looks potentially useful, but I am currently using TBGRABitmap to draw into a TImage TCanvas. If I were to try this technique, I presumably have to copy a bitmap to the display. I'm not at all sure how to do that.
I'd prefer their second approach, which is to "create and draw into a borderless window the size of the display". This also seems safer than taking over the display. I'm hoping there is a simple system call to turn on display mode.
Cheers,
Frederick