Callback: Construction stage changes

Construction stage changes (1C)

Called when the building changes its construction stage (during normal gameplay, that means exactly four times). Can return the same values as callback 1B. Variable 40 contains the new stage. You can return FF for stages that don't have animated graphics to save resources.

Like all animation callbacks, if the high byte of the result is nonzero, it will be interpreted as a sound effect number, and the corresponding sound effect will be played at the tile.