capture button under Linux broken?

I did a couple more tests on Java 3D rendering since my first try gave erratic results. I did successfully get a screen shot using shift>prt sc - but otherwise no difference from the first try - the opacity control and the screen capture button would not work.

The one actual rendering error I did get was corrected when I completely rebooted my machine, so I assume it is an artifact of the "memory leak" problem.

I don't have a Linux system, but I would be interesting to know if you could obtain opacity control on such a machine using Alice's software rendering option.