As to your suggestion that the implicit behaviour of a doubleclick is a problem, I think you're a bit off the mark. Users know that a doubleclick will 'Open' whatever they click on, there's no ambiguity there. The confusion only occurs when the user doesn't exactly know what it is they're doubleclicking on.
users must be able to differentiate between executables and documents.
interfaces must be clear and explicit when it comes to helping the user differentiate the two.
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