[Pharo-project] NBOpenGL error every third execution of example

When I do the following with the latest version of NBOpenGL, I get an error: FrameBuffer status: unk error on the third (4th?) evaluation of GLTTRenderingDemo new openInWorld. This happens whether or not another OpenGL example is open. The pattern repeats: 2-3 evaluations work and then the 3rd or 4th has an error. I have seen this error before but didn't realize how easy it was to replicate. Lawson