This is a simple extension to smart_field_contrains plugin,
to allow textareas to also have a maxlength (which is non WC3 conform).
The maxlength attribute can be enforced via e.g. jQuery CharCounter plugin.

Setup

script/plugin install git://github.com/pluginaweek/smart_field_constraints.git
script/plugin install git://github.com/grosser/smart_field_constraints_textarea.git

Author

Michael Grosser
grosser.michael@gmail.com
Hereby placed under public domain, do what you want, just do not hold me accountable...