Mac Forum / Applications / Firefox / Mozilla / August 2005

Mozilla hasnt been developing for 9x since version 1.2.1, so any SDKs
would be out of date and unusable with newer code

From http://wiki.mozilla.org/Gecko:SDK
"When downloading the Gecko SDK, it is important to choose the version
that corresponds to the earliest version of Mozilla that you wish to
target. In other words, you shouldn't download the 1.7 Gecko SDK if you
want to use your component with Mozilla 1.6. This is important because
binary compatibility is ensured only with future versions of the Gecko
runtime"

I dont see a SDK for versions preceeding 1.6

The Gecko SDK doesnt seem to be available for Macs from Mozilla, only
Windows and Linux. There is the following note on the above website tho,

"The Gecko SDK is not officially supported for other platforms, though
for some other platforms it may be available under the contrib
(http://ftp.mozilla.org/pub/mozilla.org/mozilla/releases/mozilla1.7/contrib/)
subdirectory. The Gecko SDK is also output by a normal Mozilla build
under dist/sdk."