It doesn't work. Closing the last tab closes the window.

Does NOTHING. FF still closes.

This doesn't really do anything. It doesn't even have an icon in the toolbar or "More tools...". Thanks to the user who mentioned about:config browser.tabs.closeWindowWithLastTab in their review, I don't even need an extension for this.

Still closed the Firefox window after closing the last tab. Best solution I found: set "closeWindow" in about:config to false!

Piece of crap. Closing last tab STILL closes browser. WTF! Where is "Last Tab Close Button" extension?? It worked perfectly until sh*thole latest FF upgrade.

This extension does not do what its title says. It does not prevent closing of Firefox when the last tab is closed. In the description, it does say that it will prevent Firefox from closing if there are pinned tabs, but that is useless for me, at least.