Developers Note: Screen Widget Model Classes

[Adrian Crum]

Just a friendly reminder to the OFBiz developers and committers: The 
screen widget model classes should not have their state altered by 
renderers. That is not thread-safe and it results in undesirable behavior.

I know it's easy to forget - I just deprecated some methods that I wrote 
where I made that mistake. :-)

It might help to think of the widget model classes as being immutable 
(though technically they aren't). Once they are constructed and put in 
the cache, they shouldn't be changed.

If you see code where a renderer calls a model's renderXxxx method, and 
inside that method the model's fields are being changed, then that is a 
no-no.

-Adrian