Create bitmap of Form instead of Repainting

Hi
I'd like to capture form canvas before redraw, after change of some
visible components on it (e.g. after page change in TNotebook).
Then I'd like to make transition between "old" and "new" form states.
Any idea how to capture bitmap of form.canvas ater change without redraw
of it? Is it possible to do "virtual" changes without visual effect or
without flickering form contents?

Tanks in advance
Radek Przybyl