Evolving the UI

while it is true that separating logic from presentation is an intriguing idea I doubt that this can be consequently achieved in every kind of application. Text-based forms may work, graphical applications probably not. And knowing the 4D forms editor and all its CAD-like abilities to group, layer, automatically align without "pixeling" around and still adapting different screen sizes and different UIs like Aqua and Windows XP I think it's more a matter of form editor quality.

Separation of logic & presentation can be achieved - of course there will be a very thin layer kind of delegating things back & forth. I have blogged numerous pointers dealing with this topic. Especially with modern forms-based editors, it's hard to resist mixing presentation & logic code - causing major problems in testability and maintainability later on.

Quality of forms designers is an interesting topic. As long as the resources generated by the forms designer are in a text-based format and visual properties are defined in a "css-like" way - things would look pretty good for rapidly evolving the "look" of a UI. I have yet to see such a forms/resource editor (for general purpose development environments), though.