From computerworld

"Mozilla will add a new lockdown feature to Firefox 3.6 that will prevent developers from sneaking add-ons into the program, the company said.

The new feature, which Mozilla dubbed "component directory lockdown," will bar access to Firefox's "components" directory, where most of the browser's own code is stored. The company has billed the move as a way to boost the stability of its browser.

"We're doing this for stability and user control [reasons]," said Johnathan Nightingale, manager of the Firefox front-end development team, in an e-mail today. "Dropping raw components in this way was never an officially supported way of doing things, which means it lacks things like a way to specify compatibility. When a new version of Firefox comes out that these components aren't compatible with, the result can be a real pain for our shared users.

"Now that those components will be packaged like regular add-ons, they will specify the versions they are compatible with, and Firefox can disable any that it knows are likely to cause problems," Nightingale added."

Read more: http://www.computerworld.com/s/article/9141044/Firefox_3.6_locks_out_rogue_add_ons