In Firefox version 3.x when you closed the Firefox browser with many tabs open, you were shown the ‘Saving Tabs dialog’ asking you if you want to save the tabs. If you chose to save the tabs, those tabs were opened next time you started Firefox. But starting in Firefox version 4.x this feature is disabled. If you close the Firefox window, all tabs are closed and not opened the next time. This is irritating. If you want, you can enable the Save Tabs dialogs on exit. Here is how :
- Start Mozilla Firefox.
- Type about:config in the location bar and press Enter.
- Firefox will show a warning. Click on the button labeled I’ll be careful I promise! to proceed.
- In the Filter field type showQuit. You would see a preference named browser.showQuitWarning as shown.
- Double-click on browser.showQuitWarning to change its value to true. The true value means that the Firefox will show you a warning when you try to close a Firefox window with multiple tabs open.
- After changing the value, restart the browser for the changes to take effect.
Note : This requires that you have set the value of browser.tabs.warnOnClose to true as well. This value is true by default, but if you have changed it to false, then turn it back to true.