STEP 1: Create 2 object, i use one shape and text on it, select objects (SHIFT+Click on each object to select), right click on the objects, Grouping-Group as Sprite
STEP 2: Right click on sprite, Grouping - Group as Button


STEP 3: on the Button Panel, check on Has Separate Over State

STEP 4: Expand the button state by clicking on the + sign, open the sprite at OVER STATE, you'll see the shape and text are in the sprite.

STEP 5: last, right clik on timeline at first frame of the text, Effect - Fade - fade In

STEP 6: play the movie, rollover your pointer on button to see how it works



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