WPF: What could cause a DataGrid to call IEditableObject.BeginEdit/EndEdit but never IEditableObject.CancelEdit

When I start editing my grid IEditableObject.BeginEdit. And if I leave then IEditableObject.EndEdit is called. However, if I press Escape then IEditableObject.CancelEdit doesn't get called.开发者_StackOverflow中文版

This was working before, so I'm not sure what I did to break it. Or even what can break it.

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If you have a template column and one if the bindings has UpdateSourceTrigger=PropertyChanged then you break the ability to cancel edits.