Mode-X triple buffering and retrace interrupt simulation.
This program demonstrates the use of triple buffering. Several
triangles are displayed rotating and bouncing on the screen
until you press a key. Note that on some platforms you
can't get real hardware triple buffering. The Allegro code
remains the same, but most likely the graphic driver will
emulate it. Unfortunately, in these cases you can't expect
the animation to be completely smooth and flicker free.