Don't autoinsert default handler ('on mouseup/end mouseup')?

[Brian Yennie]

FWIW, I've had exactly this problem: I wanted buttons to pass mouseUp, 
but if I accidentally saved them with the auto-inserted empty mouseUp 
handler, it broke.
My vote would be for it to set the script to empty if it's identical to 
the auto-inserted script.

> I don't know how many of you have run into this same kind of thing, 
> but it's
> an annoyance to me so I thought it might be an annoyance to others as 
> well,
> and if we're getting set to get a new IDE, now would be the time to say
> something. :-)