[solarkraft]

Not all. Many include WebKit based browsers (pretty much all except Firefox are, and Firefox is too heavy for many).

[ktjfi]

I also blame the Mozilla Corporation for that: including WebKit in your software is a piece of cake. So that's what the default browsers of GNOME/KDE/etc do. Gecko not so much (in fact, has there been any effort in this arena, after XULRunner was discontinued?)

[alex_duf]

Gnome is literally running using Firefox's technology

[solarkraft]

Please elaborate. I don't know any project embedding Gecko.

[Vinnl]

For Android at least they're working on https://github.com/mozilla-mobile/android-components/