I've been successful autostarting a number of different programs under LM12 LXDE with one important exception: Thunderbird.
This is the method that I use:
1) Copy the .desktop file of the program to autostart from /usr/share/applications into /home/[user]/.config/autostart
2) Menu > Preferences > Desktop Session Settings to enable/disable the program under Automatically Started Applications
Unfortunately, Thunderbird does not work for me using the above method. Anybody know why this might be?
I suppose I could try another method to autostart Thunderbird, but would appreciate any ideas.
[Edited to mark as solved.]