> Yes, general preference for all balloon help seems more reasonable.

Please reconsider.

Some applications may define their own balloons and want them to appear 
(or let the user choose), while at the same time allowing other balloons 
such as the message lists ones to be turned off.

It is a matter of workflow and management of the attention of the 
application user. I think there are no hard rules here.

So having the possibility to turn off help balloons selectively is a 
good thing IMO, even if it is a little more complex to implement.

Stef