We need an option somewhere to explicitly set a default desktop. Example: Sysadmin wants KDE to be the default desktop, but doesn't wish to uninstall GNOME in order to achieve this. Bug #451850 is the equivalent of this in gdm. The favored method of doing this for gdm is to make it read an option from gdm's custom.conf. It would be wrong for ldm to read gdm's config file. So I am now considering adding a new option to LDM like LDM_DEFAULT_SESSION where it can be configured specifically for ldm. Discussing this on upstream ltsp-developer list.