grog: Since you seem to be the only other person using this,...
.. have you noticed that sometimes the left panel does not go transparent? If I run rndback from the command line, there are no problems. If I run it from the menu, the left panel sometimes doesn't go transparent on the first run.
And thanks for the elegant random number solution. I couldn't seem to find a good shell-based way to get a random number, it didn't occur to me to use awk's random number function. Very clever!
I will put out a new version of the package, with the better random number and a more refined way of setting specific panels to specific transparencies.