Be careful with old versions!
These versions are displayed for reference and testing purposes. You should always use the latest version of an add-on.
It also fixes a bug with urlencoded accelerators.
It also adds splash pages for install/upgrade/uninstall.
It also adds the much requested feature that selected menu items open in new tabs.
It changes the links for "Find More Activities" to point to the new ieaddons site. This required some code that actually modifies the ieaddons site to work with Firefox.
It also integrates search engines in the same way that Activities on IE8 does.