This is excellent. I hope you don’t mind if I use your suggested comments verbatim!

I think live validation is a great idea. I actually did this the day before you posted this in Slack (joined a mapping event with ~25 people as “embedded validator”). It was very informative. It’s important to sound very friendly, don’t want to intimidate people.

@martien-vdg After watching this video https://www.youtube.com/watch?v=ACC1HXfenKA&ab_channel=HumanitarianOpenStreetMapTeam (posted by @Kraan46 in the Validation Slack channel) I have been using both the “Inline_Validation” and “Missing Maps / Youth Mappers Validators Checks” Map Paint Styles in JOSM when validating. The effect is to very clearly highlight problems like overlapping buildings, etc. What if the ID editor had this kind of rendering built in? Overlapping buildings, red. Un-squared buildings, yellow. Building intersecting road, orange. It could be an option, like New Mapper Mode.