Grabbing screen

I want to activate my program and have displayed (preferably in TImage)
whatever was on the screen immediately prior to the program commencing.

I can do this by pressing <Print Screen> button, then running the program,
then loading the resultant image from the clipboard into the TIMage. I want
to avoid having to do anything extra than just running the program.

Perhaps one way would be to activate the <Print Screen> button from the
program after initialising the form, but before displaying it.....

If you think this might work, can you tell me how to call the <Print Screen>
action in software.

If you have any other ideas, I'd like to hear them.

Thankyou..

Laurie Bisman..