Synergy allows the use of several monitors, share keyboard and mouse. You want a third monitor in your laptop? you got it, bruh.
But beware, you just need another computer in the same network. No big deal.
But sometimes can be a pain in the ass, because the client and server have to be the exact same version. This changes from repo to repo, but i* got it to work* with the next lines:
wget -q -O - http://archive.getdeb.net/getdeb-archive.key | sudo apt-key add - sudo sh -c 'echo "deb http://archive.getdeb.net/ubuntu trusty-getdeb apps" >> /etc/apt/sources.list.d/getdeb.list' sudo apt-get update sudo apt-get install synergy
Same versions, yo.