I get the same behavior of not having this error message in a plain lxde session but still get the same behavior on up to date vivid build.
To do this I ran sudo apt-get install lxde in vivid and then switched user to the guest session and then tried launched a guest session and did not get the message in plain lxde.
I get the same behavior of not having this error message in a plain lxde session but still get the same behavior on up to date vivid build.
To do this I ran sudo apt-get install lxde in vivid and then switched user to the guest session and then tried launched a guest session and did not get the message in plain lxde.