How to create a shortcut that would bring the restart-shutdown menu?
This worked in Freya but doesn't work in Loki.
Go to System Settings > Keyboard > Shortcuts > Custom.
Add new command by clicking the + button and add:
gnome-session-quit --power-off, then press keys to create shortcut.
Log out and in to be able to use the new shortcut.
I think it looks even more elementary OS-style than the default shutdown menu.
The command for the default shutdown menu is (as provided by this answer):
dbus-send --session --print-reply --dest=com.canonical.Unity /org/gnome/SessionManager/EndSessionDialog org.gnome.SessionManager.EndSessionDialog.Open uint32:2 uint32:0 uint32:0 array:objpath: