I guess the root question is why do you need the screen resolution? Web Dynpro isn't design to be screen resolution specific. That is why it is flow layout based and not pixel coordinate based. Generally the use of % based width/height parameters will allow the content to adjust to the screen size. Even if you had the screen size, what you reall need is the browser window size. This can change even the user resizes the browser. Even if you could get this value via ACFExecute or something like that, you wouldn't have an event to let you know when the browser was resized.