We use mask to identify the visible region of any sprite. Masked
sprites work as a viewport. Simple masking is based on 5 steps
a) Create a rectangle or circle or beizer shape
Group it as sprite
c) goto sprite properties tab and check masked (checkbox)
(when sprite is opened)
d) now draw what ever you need as well as give effects.
all the effects and object should be on front and the
shape created initially should be on the back of all
which is treated as mask.
e) run the movie, you will see no object is going out of the
region you created initially (either rect,circle,beizer).
Note: If some region of buttons going out of mask will not