Abstract: Non-limiting examples of the present disclosure describe programmatic generation of a user interface for display on a processing device. A display class is determined from a plurality of display classes based on a detected display size of a processing device on which the user interface is to display. Prior to instantiating a user interface window, a stored user interface definition is identified and interpreted. The stored user interface definition comprises at least one programmed command object. A displayed user interface is instantiated on the processing device, where the displayed user interface comprises at least one user interface element. The user interface element is programmatically generated by translating the programmed command object of the user interface definition into the user interface element based on operations set in accordance with the determined display class. Other examples are also described.