Vertical Tabs

This Firefox 4 add-on arranges tabs in a vertical rather than horizontal fashion. It is heavily inspired by and borrows ideas from the excellent Tree Style Tab add-on. Note: This add-on is undergoing development, much as Firefox 4 itself. Its goals are: * Ability to arrange tabs in groups (instead of arbitrary trees) plus some group-related features (Collapse group, tab previews, etc.) * Very few other features and hopefully little or no preference settings. Instead a good JavaScript API shall be provided for other extensions (e.g. Jetpack SDK based) to provide additional features. * Native look and feel. * Readable and maintainable code, taking latest Mozilla practices into account. No EVAL() hacks.