I searched for this a lot, but I couldn't find a solution for this 'bug' as it's called here: http://fcontheweb.com/articles/scrollwheel/
Please, click on first flash, and use mouse wheel, then click on second flash and use mouse wheel again. Now You know perfectly what 'bug' I mean.
The thing is, I believe this bug can be solved WITHOUT externalinterface. This chat is made with AS 3: http://www.kongregate.com/games/UnknownGuardian/game-development-room-gdr Open 'codebox', hold ENTER to make a hundred of lines or so, and then test your mouse wheel.
It doesn't use any externalinterface technique (both obviously as it's Kongregate, and confirmed by author), just mx.component.textArea that itself implements the scrolling nicely.
I couldn't achieve that with even.preventDefault or stopPropagation. Any ideas?
E: Thank You, divillysausages! The question still isn't answered in 1% - what is textArea component's workaround?