Hey! Since the Sys class was removed in LWJGL 3, how do I send alerts to the user?
LWJGL3 has bindings for https://github.com/mlabbe/nativefiledialog
You can download a bundle of LWJGL3 containing nfd using: https://www.lwjgl.org/customize
Nevermind: I just realized it only covers file open dialogs and no message dialogs...
The tiny file dialogs (https://sourceforge.net/projects/tinyfiledialogs/) bindings (tinyfd module in LWJGL) should have everything you need.