maxlength-function only works as a shortener?

With for example 50/400 one can set the width of textarea to “50” and the amount of characters to “400”. That works fine: Messages will be shortened to “400”… and sent… There is no “red-border-message” that a message is too long. Is that correct or is it a bug?

And is it possible to do something like this?: Twitterlike dynamic character count

Anyone here who uses this plugin with cf7?

Greets

http://wordpress.org/extend/plugins/contact-form-7/