Flash is random
If you’re not a Flash programmer this may not entertain you – so move onto something funny, if you are please read on…
If you have a two movie clips – one laid over the other, flash is ‘clever’ and knows the user can’t see the one underneath and therefore deactivates mouse handlers – onPress, onRollover etc when the mouse moves over the MC overlaying it.
Another test (s3 inside s2) shows all handlers of a MC within another MC will never be called if the containing MC has any handlers set.
Check out this movie showing what i mean