Tabbed browsing is inclined somewhat to the right. When new tabs are opened in Firefox, they open to the currently open tab. When a tab is closed, the tab on its right becomes active. If this is the way you like your tabs to open and close, then browsing should be fun but if you need tabs to open differently, the TabsRight extension for Firefox should help.
TabsRight is simple and straightforward; it still opens a new tab to the right but when a tab is closed, this extension makes the tab on the left of the closed tab active. It also closes tabs when they’re double clicked. In the above screenshot, when the Wikipedia tab is closed, the tab with AddictiveTips will become active instead of the Facebook tab.
The usefulness of this extension is based purely on personal reference; how you want your tabs to open and close. If the default way of opening and closing tabs doesn’t suit you, this is an easy solution made interesting by the fact you can double click a tab to close it. Double click to close option has to be set from Add-on options and is not enabled by default when the extension is installed.