I already tried that, but it was even messier: it seems the offset of the bitmap is calculated with the speed and the ticks since gamestart. Thus, if I change the speed in mid-game, the offset is recalculated and the bitmap hops. If I slow it gradually, it hops even more, at each change of the variable a little (even if it is a rather insignificant small change).

Adrian: I thought of that, too, and I already used the tutorial. I just thought if anyone had a great idea how to solve the problem, I wouldn't have to avoid a moving sky.

Thanks anyway for the answers.

Gnometech