InlineHistory inserts bug activity inline with the comments when viewing a bug.
It was derived from the Bugzilla Tweaks Addon by Ehasn Akhgari.

For technical and performance reasons it is only available to logged in users,
and is enabled by a User Preference.

It works with an unmodified install of Bugzilla 4.0, 4.2, and 4.4.

If you have modified your show_bug template, the javascript in
web/inline-history.js may need to be updated to suit your installation.