ActionScript 3.0 :: Text Input Control On Top Of Native TextField Class

I am creating a text input control on top of the native TextField class. I am trying to make the input text field itself behave in such a way that hitting Enter when focused and typing, instead of adding a line feed, produces a kind of "submit" event from my control, clearing the "submitted" text input. The described above works quite well. My problem is that I currently rob the users of my control the simple line-feeding ability - instead of a line-feed, a "submit" event is dispatched.

Obviously my control is designed for sending text rapidly, but it is also multiline so I want people to also be able to insert newlines. Think of this as a chat text input control. What I thought about is, somehow capture Shift+Enter and make it behave as Enter usually does. This has proven to be absolutely impossible, and I know a thing or two about Flash Player.

Part of the problem is, Shift+Enter by default does not itself produce a newline (even though pretty much everything else that types in any OS, does) and I cannot patch the event - f.e. by setting 'shiftKey' property to false at capture phase so that the event moves on as if Enter was pressed instead. How to do this, sort of replicating a TextField entirely down to a caret and all?