Thanks for your response.
Neon UI is my most popular one for some reason.
Metal UI is one of my favorites to share because it goes to show that you should never need to use Swing again.
An example of the fun things you can pull off in Scene2D.UI.
There's more in the link I provided.
And yes, I'm fully aware of Spine's relation to LibGDX and I'm forever grateful for your contributions to the library. Spine is the one software I use to explain why I still use Java and LibGDX.