When you select Close other Tabs from tab context menu, Firefox shows Confirm Close dialog alerting “You’re about to close x number of tabs, Are you sure you want to continue?” if you click “Close tabs”, other tabs will be closed, pressing Esc or clicking Cancel makes no changes to the browser. This turns out to be annoying. Its not accidental move by user and seems to be intentional where he has to right click on a tab and select Close other tabs. So why this annoying dialog comes in user’s way ?
With more user requests Mozilla has finally added a hidden preference in about:config in Firefox 17 beta, all you need to do is turn that preference value to false.
Turn off Close other tabs warning in Firefox
1. Visit about:config in browser
2. Find browser.tabs.warnOnCloseOtherTabs preference and double click to change its value to False.
That’s it you don’t encounter this annoying prompt again when close other tabs menu item is selected.