This one isn’t code related, but I come across this enough in Linux Mint VMs that I’m saving it here for myself and anyone else that may find it useful.
I currently use Linux Mint as my development environment. When I’m using Firefox (39.0+build5-0build0.14.04.1) and closing a browser window containing multiple tabs, I always get prompted by Firefox: “Do you want Firefox to save your tabs for the next time it starts?” There is a checkbox for Firefox to not raise this warning in the future, but no matter how often you check it you will still get the warning.
Open the ‘about:config’ page.
Set browser.tabs.warnOnClose to false (if it isn’t so set already).
Set browser.tabs.warnOnCloseOtherTabs to false.
Set browser.warnOnQuit to false.