The Scale alteration will cause the sprite to incrementally change size. You can scale on the x or y axis or both.
FireFox may fail to launch completion events if sprite size reaches 0.0. Therefore, also set a minimum size of 0.01 or something smaller if necessary.

create routine as Start launch horse end create sprite from horse12.png as horse where x=100 and y=100 having alt=(sub create scale as f where rate=-0.5 and until=0.1 and type=y end) end


specify a routine to run when the scaling is complete.
a scale rate per second. Use a negative value to shrink and a positive value to grow the sprite.
specify in which direction to scale the sprite. If type is not specified the scaling is performed both ways.
the value at which the scaling should end. Be sure this number makes sense with respect to the initial size of the sprite and the rate being negative or positive.