Hey,
With winter fast approaching, I broke out xsnow today. I use compiz-fusion, and when I run xsnow it will not allow snow to fall behind any windows that are currently open, even after I close the window. And I can't "shovel" snow by moving a window on top of accumulated snow. If that description doesn't make sense let me know and I will post screenshots.
I mention that I use Compiz because on a hunch I switched back to metacity (using the Compiz Fusion Icon) and the problem went away. I tried most of the relevant commands given in the xsnow man, but nothing seemed to help.
I don't have the Compiz snow plugin, but I would prefer to use xsnow anyway.
Thanks! jim