Gecko SDK is a package that provides header files, libraries and tools needed to build Mozilla XPCOM components.
This document explains how to build the Gecko SDK on the Mac OS X platform.
mozilla.org provides the SDK for the Windows and Linux platforms. I needed one for the Mac OS X. I looked around and as far as I could see, there wasn't one to be found.
The alternative was to download the whole Mozilla source tree and build it. This is not a very practical approach. Mozilla is a large project with hundreds of components and the build process can take hours. Gecko SDK is a small part of Mozilla and building the whole thing just for a few libraries is a huge waste of time and space.
The idea is to download the complete Mozilla source code tree, but to build only the needed parts.
Here are the steps I took to build the Gecko SDK on Mac OS X:
./configure --enable-standalone-modules=xpcom
from the root Mozilla source directory.
make
command to build only the XPCOM part.
The build takes only a few minutes and voila, you have an SDK package located in the dist/sdk
directory of the Mozilla tree.