Another new thing that came out with Firefox 29 is a sexy new customization interface. We wanted to make UI customization something that anybody would feel comfortable doing, instead of something only a few mighty power users might do.

The new customization mode is accessible by pressing the Menu Button (

http://mikeconley.ca/blog/2014/06/19/australis-performance-post-mortem-part-5-the-customize-mode-transition/