Hi,
I'm not so sure this is the problem after some further experimentation. It seems like with multiple canvases, the individual scene are just not fully rendered sometimes. I made some improvements to make the simple test classes easier to follow. It is interesting that the same problem behavior is exhibited whether separate JFrames or JInternalFrames are being used:
RotatingCube.javaMultiJFrameTest.javaJDesktopTest.javaMyScene.javaMyThread.javaTom