XML based generation of Rich and Native
UI's is gathering momentum, it might also be a point to understand
the complimentary relationship that exists between XForms and these XML based
GUI generators.
BTW - Here is a
great XForms presentation that helps aids in the contextualization
of my prior comments.
The actual Macromedia MXML (Flex)
review by Jon Udell follows:
After a decade of web-style development, I'm sold
on the idea of using markup languages to describe the layouts of
user interfaces and to coordinate the event-driven code that
interconnects widgets and binds them to data. The original
expression of that model was HTML and JavaScript, but variations
have flourished. Mozilla-based applications have been using
XUL (XML User Interface
Language) for years. The Laszlo Presentation Server
uses a description language called LZX. Microsoft has previewed
XAML (Extensible Application Markup Language) for
Longhorn.
Now comes MXML
(Macromedia Flex Markup Language), the latest development in
Macromedia's ongoing quest to reposition the near-ubiquitous Flash
player as a general-purpose presentation engine for rich Internet
applications. With XML markup at its core, Flex is inherently IDE-
friendly, and Macromedia has two IDE initiatives underway. One,
code-named Brady, builds on Dreamweaver MX. The other, code-named
Partridge, leverages Eclipse.
Full Review:
http://www.infoworld.com/article/04/03/29/13TCflex_1.html
Also see XML for UI Languages:
http://xml.coverpages.org/userInterfaceXML.html
Nothing stops any of the engines
mentioned above (proprietary user interfaces as per the diagram
below)