First of all I want to say thanks for your amazing framework. Now there are some features I would like to see, but they do not have a too high priority as GLFW runs fine without them.
I would like to see input handling for the lock keys - caps lock, num lock and scroll lock - and the print screen and pause keys. Probably these are not easy (otherwise they would be in already), but it would definitely be nice to see them supported.
Also it seems a bit awkward to me that when using the key (rather than the char) of the numpad, this is influenced by shift and by num lock - while I think neither should be the case.