I'd be grateful if an option could be added to the preferences page, so that the user can request that documents which specify a Schema or DTD must be validated each time the document is saved.
I have to admit that I'm lazy and forgetful, so I rarely call the validate feature in the XML menu. But I do want to know about it if my XHTML or sitemap file are failing to conform to their DTD or Schema, so it would be very welcome to have a warning pop up if I try to save and the document is not fully valid.
To avoid frustration, a "save anyway" option would need to be added, just in case a user needs to save an invalid copy halfway through making an edit.