When using lxdm with userlist disabled (which is strictly recommended for security reasons), the gtk greeter does not clearly separate between the username entry and the password entry. There should IMHO for security reasons be two entry fields labeled with "username" and "password". The gdk greeter does this better by displaying "username" and "password" in the entry fields (which is IMHO suboptimal -better would be two have to entry-fields).
Great work! Simple and small display manager!