It would be really useful to have a simple way of stopping taps/clicks from propagating to lower objects or layers.
Whenever you have an on-screen toolbar or menu or a pop-up it is always a hassle to set up control variables to stop buttons from activating what's below them when tapped.
Now to think of it, triggering the whole stack of overlapping objects is hardly ever the desired result.
Just as an example, in Corona SDK you can "return true" in the click listener of an object, which, upon receiving it, immediately breaks the click event (thus it not triggering in any object below).
I'm not sure if it is possible due to how touch/mouse events work in Corona, but it would be a very handy little feature.