JOGL GLSL ShaderProgram/State: Release of an unlinked ShaderProgram shall not throw an exception -> avoid calling useProgram(.., false).
GLPixelBuffer.dispose(): Set diposed:=true to allow isValid() to work properly; GLJPanel: Rely on GLPixelBuffer.requiresNewBuffer(..) for each frame, don't use local pixelBufferCheckSize (buggy w/ singleton)