i have similar interest in scaling actors for depth etc. the examples here:
viewtopic.php?f=2&t=9427&p=93068#p93068 have helped me learn alot how canvas can work and am far far from finishing my explorations.
i played with an example 'zoom' and learned how to scale actors while preserving persistance in their animations and gave them scale origins at creation and scale limets.
i'm posistive you can tell it to scale up on creation to desired value, then let that value be an event to scale back down and min scale value event back up agian.
the scale transisions will occur in draw events- just look at my version: simply use the script in the press up key/down key events. but instead of using a key event, just paste it in a draw event and it should do it for each re-draw on its own. (like a pulsating effect?) will require scripting the met value events to complete this. i can only trial and error off what i've done so far.