Paso a explicar.
Abrimos una terminal y ejecutamos:
# su
# gedit /etc/systemd/logind.conf
Descomentamos la linea:
#HandleLidSwitch=suspend
Y deberia quedarnos asi:
HandleLidSwitch=suspend
Guardamos y probamos.
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There is a simple way to enable the suspend mode when you close the lid of your notebook, because Gnome 3.10 not have this on the configuration form, you only need edit one line of the file logind.conf with "root" user.
Open your terminal and insert:
# su
# gedit /etc/systemd/logind.conf
Uncomment this line:
#HandleLidSwitch=suspend
Should be well:
HandleLidSwitch=suspend
Save and test.