From : Gregor "B." Rosenauer (e9425635@stud1.tuwien.ac.at)
Subject : Clear a sprite in Blitz mode
>Does anyone know how to remove a sprite from the screen (I am actually
>using the new display libs)?  Currently I just move (hide) it beyond the 
>displayable play area that the player sees.

In my game, I use a "dummy"-sprite (1x1 pixels, blank) that I display when I
want to turn off a sprite.