On data management controls (like the grid and the listview), if they are bound to an ajax remote data source and an error occures, it will silently ignore it and accept the changes. You listen to the error event on the data source to display the messages, but that wont stop it from accepting the changes. You can add a single occurrence listener on the grid's data binding event to prevent it, but you are starting to get into weird hacks. Then theres the listview, which is an even uglier hack.

Not only should this be standard behavior in the first place, but it's a pain to even get it to work with hacks.

Please change the behavior or at least add an option to prevent accepting bad data that didn't even get saved in the database.