move-and-resize-sheet definition

[admich]

move-and-resize-sheet isn't defined in term of move-sheet and resize-sheet as suggested in the specification (Sec. 7.3)

(defmethod move-and-resize-sheet ((sheet basic-sheet) x y width height)
  (move-sheet sheet x y)
  (resize-sheet sheet width height))

Using the specification suggestion will be better from a maintenance point of view.