[Twisted-web] How do you customise the Freeform form-error message

[Richard Wall]

When a form error occurs, the form-error slot gets filled with the text
"Error:". Is there a way to customise this? Or could the default at
least be expanded a bit? eg Error: There were errors in your data,
please check and try again"

Having browsed through the source, it looks like it might be possible to
summarise in the form-error slot those fields which didn't validate. Eg
Error: Name, Age

Thanks.
-- 
Richard Wall