Possibilities to employ/control/“embed” the gecko rendering engine?

Question

What is the current way to go if you want to employ/instrument/"embed" the gecko rendering engine in a separate application? Is it to write a XUL based application and use libxul? Are there any up to date resources available, such as tutorials?

I need to display and maybe print web pages, load custom CSS, execute java script, all done locally. There are so many outdated resources, it's hard to figure out what's the proper way to achieve this. Even the official Mozilla site (Embedding Mozilla) points to deprecated resources. There is a link to a new API (NewAPI), that should simplify embedding, but it seems unmaintained and incomplete.

Answer 1

The supported way to do this would be developing a XULRunner application. XULRunner is the stand-alone version of the Gecko engine, it can run any XUL-based applications. In particular, an application can use a <browser type="content" /> tag to load and display web pages the same way Firefox does it. Getting started with XULRunner is a nice introduction and there is more documentation.