Firefox has it’s own layout language called XUL that is used to style and design much of the UI inside Firefox. If HTML is so great why did Firefox need XUL? The reason is that HTML and CSS are inneficient at describing user itnerfaces, designer intent and basic design. Google Chrome’s UI? Nope. Safari UI? Nope. Internet Explorer? Yeah Right.
Standards people, it’s all about standards! Sure.
If the standards are so great and the browser makers claim great performance why aren’t the core bits of browser user interfaces built using the very same tools?
Parts of Chrome’s UI is in HTML/CSS. Browser history, download history, and extension manager are all HTML. Error interstitial pages are also HTML (e.g., SSL errors or malware blcks). The bookmarks manager is also in the process of being migrated to HTML/CSS as an extension, because extensions are just HTML/CSS: http://groups.google.com/group/chromium-dev/browse_thread/thread/ab7724e3f5bee8bd/cb4db4d11effd20e?lnk=gst
That’s not everything, but it’s a lot of stuff.