I ran the Gears demo from command line and get the same black canvas/window. This isn't my code, so assuming this is a driver or JOGL issue. However, my Linux system's video drivers are up to date, as far is I can tell.
Dell Precision M4600
[AMD/ATI] Whistler [Radeon HD 6730M/6770M/7690M XT]
openjdk version "1.8.0_191"
OpenJDK Runtime Environment (build 1.8.0_191-8u191-b12-2ubuntu0.16.04.1-b12)
OpenJDK 64-Bit Server VM (build 25.191-b12, mixed mode)