The JOGL renderer relies on a very bad practice by storing a GL instance that might become invalid at any time

[ghost]

Hi

The JOGL 2 renderer of the version 1.4 stores GL instances that might become invalid at any time which is a very bad practice:
https://github.com/void256/nifty-gui/blob/1.4/nifty-renderer-jogl2/src/main/java/de/lessvoid/nifty/renderer/jogl/render/JoglGL.java#L19
GL2 gl2 = GLContext.getCurrentGL().getGL2();

Please never do that. I had to remove this kind of thing from several engines as it causes tons of troubles. It only works when the GL instance is never invalidated. Please never store a GL instance except in a LOCAL variable like I do in all reliable APIs based on JOGL 2.

N.B: This kind of weak construct seems to appear in several places in NiftyGUI.

[ghost]

There is a good example of what should be done instead:
https://github.com/gouessej/libgdx/blob/master/backends/gdx-backend-jogl/src/com/badlogic/gdx/backends/jogl/JoglGL20.java

[ghost]

Fixed: #207
(untested)