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9.5. XULRunner

Applications that require the Gecko engine have had to depend on the entirety of Firefox. XULRunner is the Mozilla effort to split the browser engine for applications that require only that functionality, and no user interface parts. This split provides more API/ABI stability and a cleaner build environment for applications using Gecko. Many of the applications in Fedora that previously used Gecko now are built against XULRunner.
For a current status, visit To help with development, visit
For full upstream documentation, refer to