Several changes were made in Gecko 1.9.2 that may impact plug-in developers in particular. This article provides a list of those changes.
Interface changes
The nsIPluginInstance method destroy() has been removed, since it wasn't doing anything anyway.
Mac OS X specific changes
CFM plug-ins no longer supported
Starting with Gecko 1.9.2, old-style CFM (Code Fragment Manager) binaries are no longer supported for plug-ins. CFM plug-ins have been deprecated since August, 2008.
main() no longer a supported entry point
In August, 2008, plug-in developers were informed that main() would no longer be supported as an entry point. This change has taken effect in Gecko 1.9.2. Plug-ins need to be updated to use NPN_GetEntryPoints() instead.