X window in package R-base doesn't follow compiz transparency settings

Binary package hint: r-base

When using compiz transparency effects (fading windows), device windows (I think they're x-windows) opened by the package R (R-base) do not follow the transparency rules.

Steps to reproduce:

Enable compiz opacify plug in.
Set passive opacity to arbitrary value (eg 20).
Open terminal
Start R by typing the letter "R" (without quotes)
Create a plot by typing:
    x<-1:5
    y<-2:6
    plot(x,y)

Notice that mousing onto an active window, away form the plot graphic created by R does not allow the graph window to fade.

lsb_release -rd
Description: Ubuntu 10.04.1 LTS

apt-cache policy r-base
r-base:
  Installed: 2.12.0-1lucid0
  Candidate: 2.12.0-1lucid0
  Version table:
 *** 2.12.0-1lucid0 0
        500 http://www.stats.bris.ac.uk/R/bin/linux/ubuntu/ lucid/ Packages
        100 /var/lib/dpkg/status
     2.10.1-2 0
        500 http://gb.archive.ubuntu.com/ubuntu/ lucid/universe Packages

Release: 10.04

Please advise as to what additional information you would like me to post, so that this issue can be addressed.