I am looking for a customer support chat widget for the web (e.g. like Zopim) with an "edit sent message" feature, just like in Skype.
E.g. you send a message (no matter whether you are the customer support agent or the customer) but notice an error and want to correct it. It'd be useful to have "edit message" option in that case.
Budget is not of concern at this point. It could be either hosted or self-hosted.