How do I stop Firefox opening multiple tabs

[Jimi King]

If you run a widescreen monitor with a fairly high resolution I'd recommend Firefox Showcase, specifically the Showcase Sidebar (although unlike the screenshot, I'd recommend turning off the normal tabs once you're using the sidebar), which I now couldn't live without. You'll never go back to normal tabs again.

https://addons.mozilla.org/en-US/fir...8428/943948800