I liked the Firefox option to save tabs on exit. Every time I exited Firefox 3.x, I simply click on the Save and Quit button when I am prompted “Do you want Firefox to save your tabs for the next time it starts?”. The next time I launch Firefox, all tabs are automatically opened. When Firefox updated to version 4 (and newer versions as well) this feature seems to have gone. Fortunately this feature has not disappeared anywhere, it is just by default turned off.
1. Type about:config at the address bar and hit enter.
2. Click the “I’ll be careful, I promise!” button
3. At the filter bar, type browser.showQuitWarning and hit enter.
4. You can either double click on it to change the value from false to true, or right click on it and select Toggle.