The view window extends beyond the boundaries of the screen and in large models it may not be possible to see all of the elements at the same time. However, they can all be seen in the rectangular zoom window in the top left of the view window. This displays elements as small black dots. You can move the inner rectangle to navigate around the model and bring outer elements into view.
Note: You can also move around the view window using the vertical and horizontal scroll bars, just as you can in any other Windows application.