I have a class that derives from InlineUIContainer. I want to take an action when an editing command (like ToggleBold) is performed on a FlowDocument selection that includes an instance of this class. I've tried registering for this command but it isn't raised. I've tried overriding OnPropertyChanded, but it is only called on explicit changes, not when my InlineUIContainer is part of a selection acted upon. Any ideas about how I might accomplish this?