None of the other solutions worked for me in Gnome 3.14 on Gnome
Ubuntu 14.10. What finally worked was creating .desktop files by hand.
First, make the folder ~/.config/autostart/ if it doesnt exist.
Then create a ~/.config/autostart/my-app-to-startup.desktop file for each program you want to start on login.
For example, here's what my ~/.config/autostart/pidgin.desktop file looks like:
[Desktop Entry]
Type=Application
Exec=pidgin
Hidden=false
X-GNOME-Autostart-enabled=true
Name=pidgin
Comment=instant messenging client
WHAT WORKED FOR US
edit a file linuxcnc.desktop
#!/usr/bin/env xdg-open
[Desktop Entry]
Type=Application
Exec=/usr/bin/linuxcnc '/home/ghislainvdwalle/linuxcnc/configs/Wire_EDM/Wire_EDM.ini'
Hidden=false
X-GNOME-Autostart-enabled=true
Name=linuxcnc
Comment=LinuxCNC
DONOT FORGET TO MAKE IT EXECUTABLE (vertrouwd)
Here is the specification for the keys you can place in those .desktop files. This
puts some context to that specification as to how it applies to startup
applications as well as some exceptions to those rules. Credit for this
solution goes to this Linux and Friends site.