Receiving EditingCommands on derived InlineUIContainer

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开发者_如何学C, 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?