On the chromium side, there is the Chromium Embedded Framework (CEF) which is used absolutely everywhere. Not sure about gecko situation though, but at least their JavaScript engine, SpiderMonkey, also has quite widespread use. I don’t think I’ve seen projects not related with Mozilla/Firefox that use gecko though, but perhaps it’s because I never look hard enough. It’s usually either WebKit or CEF.
On the chromium side, there is the Chromium Embedded Framework (CEF) which is used absolutely everywhere. Not sure about gecko situation though, but at least their JavaScript engine, SpiderMonkey, also has quite widespread use. I don’t think I’ve seen projects not related with Mozilla/Firefox that use gecko though, but perhaps it’s because I never look hard enough. It’s usually either WebKit or CEF.