When using com.jogamp.opengl.swt.GLCanvas under Linux with Eclipse 4.8 (SWT 3.107) an Exception is thrown in com.jogamp.nativewindow.swt.SWTAccessor class during initialization.
JOGL tries to access the member field "GTK_VERSION" of SWT's internal OS class via reflection. The class still exists but the member is no more present in SWT 3.107. I've checked the source code of OS class and it is not there any more but was in SWT 3.105 which comes along with Eclipse 4.6.
To reconstruct the problem one simply has to access a member of SWTAccessor: