lxde-common requires lsb_release as a runtime dependency
|Fernando de Oliveira
Without the lsb_release program, lxde-logout will crash when you try to run it (meaning, you can't log out out of an LXDE session). Installing lsb_release as per the book will let lxde-logout bring up the logout window, as expected.
And before you ask, yes, I have no idea why the lxde-logout program depends specifically on lsb_release. Just that it does.