full_messages format customization

Rails allows customizing error messages for particular attribute of particular model, but #full_messages return error strings in form "{{human_attribute_name}} {{message}}".

It would be nice to allow customizing full_message the same way as error messages are customized: instead of @@@ruby full_messages << attr_name + ' ' + message

have something like this:
@@@ruby
defaults = @base.class.self_and_descendents_from_active_record.collect do |klass| 
  :"models.#{klass.name.underscore}"
end
defaults << "full_error_message"

options = {
  :attribute => attr_name,
  :message => message,
  :default => defaults,
  :scope => [:activerecord, :errors]
}
full_message << I18n.t(:full_error_message, options)

This will allow customizing full error message like this: @@@yaml en: :activerecord

:errors:
  :full_error_message: Field "{{attribute}}" {{message}}