I've been looking around for GUI libraries to use with LWJGL 3 and I've seen that Matthias Mann's TWL is really popular but doesn't currently work with LWJGL3. So I stared at the code for a bit and managed to get some working parts with LWJGL 3.
It's not near perfect yet but it has some functionality. If any wants to look at it feel free to contribute at https://github.com/LacombeJ/TWL_LWJGL3
And I'm still learning LWJGL at the moment and I know there might be some deprecated functionality but I'll try to find it and have it fixed. And if anyone wants to point me in the right direction I'd really appreciate it