Firefox Connection Configuration
The Tabbed
Browsing Tab
Hide the tab bar when only one tab is open
Default: Checked
This determines whether the tab bar is removed from the display when only one tab is open.
Load links in the background
Default: Checked
When this option is selected, if you click on a link using the middle mouse button (load in new page/tab), the focus is not given to the new tab.
152 The Firefox General Settings Dialog