Such a gesture as I mentioned doesn't need to be a new type of action at all! It could simply emulate "go into Active frame and immediately press X to close", like a virtual shortcut for 'Swipe up + press X'.
On Phys.keyboard devices it could be like 'long-press X+Space' for the same event.
It would (need to) be OS side and not change anything in the app processes really.
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Like I started saying, don't think it is a required feature, but I can definitely see the usefulness in some cases.
BlackBerry Q10 signed @ C0007CC89