In addition, it has been improved with

• feed support (including an RSS and Atom feed reader in the mail component),
  
• a modern look,
  
• restoration of browser tabs and windows after crashes or restarts,
  
• tabbed mail,
  
• automated updates,
  
• smart history search from the location bar,
  
• faster JavaScript,
  
• HTML5 features (for example video and downloadable fonts),
  
• and even support for the Lightning calendar add-on (which will issue a beta for installation on SeaMonkey 2.0 in the next few weeks).