The Mozilla Toolkit is a set of programming interfaces (APIs) built on top of Gecko which provide advanced services to XUL applications. These services include:

• Profile management
• Chrome registration
• Browsing history
• Extension and theme management
• Application update service
• Safe mode
• Printing

Official references

• Structure of an Installable Bundle: describes the common structure of installable bundles, including extensions, themes, and XULRunner applications
• Extension Packaging: specific information about how to package extensions
• Theme Packaging: specific information about how to package themes
• Multiple-item Extension Packaging: specific information about multiple-item extension XPIs
• XUL Application Packaging: specific information about how to package XULRunner applications
• Chrome Registration
• Printing in XUL Apps

See also

The following developer pages contain examples and discussions of particular topics:

• XUL
• XUL overlays
• Developing extensions
• XULRunner
• Developing themes
• DOM
• RDF
• Storage