1. A method comprising: inputting a first constraint image graphically establishing size information of a plurality of user interface window items with respect to a first window size; inputting a second constraint image graphically establishing size information of said plurality of user interface window items with respect to a second window size; deriving program code for dynamically generating a user interface window of a third size, wherein said program code comprises interpolative formulas for sizing said plurality of user interface window items for user interface windows of various sizes between said first window size and said second window size; and generating said user interface window of said third size and having said plurality of user interface window items disposed therein, wherein a size of each of said plurality of user interface window items is determined as a function of said size information of said first and second constraint images.