on-move in window<%>

Called when the window is moved. (For windows that are not top-level windows, ``moved'' means moved relative to the parent's top-left corner.) The new position is provided to the method.

• (send a-window on-move x y) -> void
     x : exact integer in [-10000, 10000]
     y : exact integer in [-10000, 10000]

  Does nothing.