[NTG-context] visualising evolution from one version to another

Hello, if you know a bit MS-Word, then you have seen perhaps the feature, that permits visualising differences between 2 versions of a document: added text in red, and deleted text stroke out. I would like to make something similar with ConTeXt: making a pdf-file from doc-versionX.tex and doc-versionY.tex with added text in some colour and deleted text displayed with \overstrikes{}. Do you have some ideas, how to do that? Cheers, Peter -- http://pmrb.free.fr/contact/