Need a general key listener

Hi, I am writing a libweston based compositor and I intend to implement the Emacs style key bindings (where the binding can be a sequence, thus they form a tree instead of a list). I found that I cannot achieve it with libweston's binding system. While I can successfully activate the bindings if I pressed the right key, but if the next key is not on the list, there is no way I can know about it and quit the bindings.

Good news that this can be easily done by a simple patch to libweston. I already implemented it and I can make a merge request very soon.