RE: rebuild children - when to do it

> 
> It's not the normal pattern. 
> 

Which is why I'd still recommend against it.  It's hard enough stopping new
people from making this mistake as is, without mixing the message with
exceptions.  If someone has to ask, then they should be told "do not change
state during the render phase".  This is even a rule in the code critic.

Once they understand why, they won't need to ask when they can violate that
rule because they'll understand the reason for the rule.

Ramon Leon
http://onsmalltalk.com