code: func (w *Window) GetPos() pixel.Vec {
  	var v pixel.Vec
  	mainthread.Call(func() {
  		x, y := w.window.GetPos()
  		v = pixel.V(float64(x), float64(y))
  	})
  	return v
  }
docs: // GetPos gets the position, in screen coordinates, of the upper-left corner
  // of the client area of the window. The position is rounded to integers.