Matthias:
Nooo. As I already said, Failsafe mode is basically useless to regular users anyway. Lets not confuse the login screen with non-understandable checkboxes. I guess one size won't fit all as far as the greeter is concerned. Good thing the greeter has a glade file that allows to easily remove or add things.
That's perhaps one nice reason for making this an extension to the .desktop file. This way people could add a desktop file for Failsafe if they (or their users) want this sort of feature. But, I was just pointing out that there are a few different ways that you could get "Failsafe" behavior. Basically it's just nice to have a feature that allows you to login without complaining about problems caused by sourcing Xsession or other scripts, or if your $HOME directory can't be accessed. Brian