Restricting space for actionscripted bubbles

I’m trying to create random sized & speed bubbles rising in a tank.

I found a code that I could adapt for the job, but I’m struggling to restrict these bubbles to a certain layer or to just rise inside the space I want.

I’ve attached the .fla for anyone to look at, they would ideally be on the ‘bubbles’ layer, and only rising inside the green tank.

I like a challenge and would usually take the time to find more info and mess about but I need this one done quick and can’t find much help!

Cheers!
:hat:

I lied… here it is!

http://www.pacific-shi te.com/hpf.rar (minus the gap)

425kb