1. A method of dynamically customizing the layout of a migratable application graphical user interface for a heterogeneous device platform, the method comprising: a) laying out a plurality of platform independent graphical user interface widgets in a platform independent presentation model as a function of properties associated with each of the platform independent graphical user interface widgets; b) dynamically adjusting the layout of those platform independent graphical user interface widgets that do not fit within a display screen of a heterogeneous device platform; c) identifying a platform independent graphical user interface widget designated as splitable among different pages that does not fit within the display screen; and d) splitting the identified platform independent graphical user interface widget among multiple pages.