The list accessible in Settings>Applications>Startup is empty by default:Here and in other places I found the idea that running this command should solve it:sudo sed -i 's/NoDisplay=true/NoDisplay=false/g' /etc/xdg/autostart/*.desktopBut it does not.
How to access and edit Startup applications in Elementary OS Freya beta 2?
startup;elementary os
The application to start is called gnome-session-properties (part of gnome-session-bin). There the list can be edited. Any changes there will then appear in the other list accessible from Settings>Applications>Startup; thus, the latter is limited only to reverting to defaults.In order to access that in the Panel Launcher (Applications), I have created a .desktop file inspired by the other such files that can be found in usr/share/applications with this content:[Desktop Entry]Type=ApplicationName=StartupAppsComment=View apps starting with the systemGenericName=StartupAppsIcon=preferences-systemTerminal=falseCategories=Gnome;Gtk;System;Exec=gnome-session-propertiesSo that it now can be found when searched or under Applications>System Tools