Turns out when I checked my lxsession had reverted to a previous version: reinstalling lxsession/0.4.9.2+git20140410-0ubuntu3 DID cure the problem, and the desktop.conf file is persistent with the line commented out. Thanks for the help.
Turns out when I checked my lxsession had reverted to a previous version: reinstalling lxsession/ 0.4.9.2+ git20140410- 0ubuntu3 DID cure the problem, and the desktop.conf file is persistent with the line commented out.
Thanks for the help.