EDIT:
Your problem is not the flickering but the setting of the height and width to 0
and then back to the old Position (Fullscreen)
Rethink your approach
using.. "Hide, Show" or "minimize, maximize" or create a Container for the Capture.
just a Suggestion.
greets
@EWeiss,
this idea of container seems more appropiated for me, but my form still will appear on screenshot?
I not want
hide/show or
minimoze/maximize, this not is good. Remember that background of Form must be erased before capture the screen.
This container could be a
TImage or what?