Gecko is Gecko

Netscape Epiphany FireFox SeaMonkey Galleon Camino Kazehakase K-Meleon Mozilla Flock

You are reading this because a user of your website is complaining that the browser user-agent sniffing you do breaks your site. The reason is because you sniff for "Firefox" or "Netscape" instead of "Gecko" in the UA. Firefox is not the only browser using the Gecko rendering engine from Mozilla.org, and all of these browsers support the same web technologies as Firefox.

Read More about Gecko

How to feature-sniff instead of browser-sniff

How to properly sniff for a version of Gecko