I've done as I saed. I had a sprite pulsing, and other sprite[player] moving with behavior scroll-to, then I understood that the effect was relative to screen position.
My first try was to set parameters on the effect box. No sucess as it would not accept my imputs.
My solving try was to do it by events, as explained above.
PS.: I didn't saw ur reply before, is there anyway to follow topics by posting on them?