You have a fascinating concept. Could you explain some of your thinking on why you think this particular paradigm is superior?
first let me clarify that i don't oppose the modal model in any way – as you said, it works just fine. My motivation was to find out whether the fluid model a) also works and b) has any advantages, and if yes which ones.
I didn't come to a conclusion so far, but I have observed some interesting stuff, both on the pro and con side: - Once understood, the interface makes navigation considerably faster - The individual space for content is necessarily smaller and - The individual content panes have to adjust to the constraint that their content can only adjust horizontally, as the vertical axis is reserved for the navigation.
I am opposed to saying that modal is inferior or something like that, it always depends on the context, the use case. In this very special case, it might be a better solution, but in many others, it fails hard ( think, for example, mail ).