Restore Synaptic Mark All Upgrades Button in Linux Mint

The Mark All Upgrades button is missing from Synaptic in Linux Mint. I think the philosophy of the developers is that you should use the Mint Update Manager with its priority system to apply system package updates. If you’re coming to Linux Mint from Ubuntu or Debian, then you’re probably used to being able to anything you want in Synaptic. In the following tutorial I’ll show how to restore the Synaptic Mark All Upgrades button in Linux Mint.