MozillaZine

Full Article Attached Open XUL Alliance Site Goes Live

Sunday May 25th, 2003

Gerald Bauer writes in with news that the Open XUL Alliance site has launched. The site aims promote XUL and encourage interoperability with a collection of XUL news articles, mailing lists and links.


#35 Re: A Rose By Another Name Is Still A Rose

by james

Wednesday May 28th, 2003 12:26 AM

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Their are lots of XML based user interface description languages, and many of them look nothing like the XUL that Mozilla uses. There are many decisions you can make when designing such a format, and people won't necessarily make the same decisions as the Mozilla developers made.

If your aim is to design a language to describe user interfaces built with a particular widget set (eg. Win32, MacOS Coacoa, GTK, etc), you would usually structure the language to match how the widgets are layed out. For instance, the "menubar -> menu -> menupopup -> menuitem" heirarchy used by XUL doesn't map well on to GTK, since the widget heirarchy in GTK is "menubar -> menuitem -> menu -> menuitem".

Another place where GUI toolkits differ is geometry management (ie. how do we lay out child widgets inside a container, and how do we redo the layout when the window is resized). This is another place where Mozilla's XUL does not match the semantics of some GUI toolkits. Implementing the XUL semantics on top of the toolkit may be impossible or prohibitively difficult. Additionally, not all the aspects of the toolkit's geometry management system may be representable with XUL in its current form.

In the case of Microsoft's UI description language, do you really think they would give higher priority to "making it compatible with Mozilla's XUL" rather than "making it work consistantly with their existing technologies"?

If the only thing in common between XUL and XAML are that they are represented in XML and describe user interfaces, then I wouldn't call it XUL. Doing so is just going to cause confusion.

Of course, since I haven't seen a XAML specification or example code, I don't know what it will look like. However, I didn't see anything in that article that would lead me to believe that it will be compatible or similar to XUL.