Just go to trisquel's menu>System Settings>Power, Where it asks you what to
do when closing the lip, chose nothing.
Be aware though, some laptops breath trough the keyboard and tend to get very
hot, which might burn or damage your laptop. I use to have that problem with
my old macbook. Just make sure your's is not one of them. You could for
instance search on the web about it, or just check it's temperature with your
hand in the bottom while it's been closed for a while. There is also some
gnome applets and programs that let you know the temperature of your laptop.
Good luck friend.
