XUL and Standards
Is XUL a standard? No. It’s an XML
application Netscape invented. (Plan to
submit for standardization in the future.)
Does XUL duplicate or compete with web
standards? No. It answers a question no web
standard now does: “How can you define a
desktop application UI using standards?”
XUL uses XML as it was intended—as a
way to define new markup languages (XML
applications) for specific purposes.