Allow navigator to scroll above/below page
Dragging the navigator's selection rectangle stops at the top/bottom of the active page. It is sometimes desirable to scroll the page even higher (perhaps also lower) so that the physical page edge is in the center of the screen. This is to avoid obscuring the active part of the page with floating windows (palette, selector, etc.) or the soft keyboard used on a tablet. The page can be dragged up manually using the mouse to achieve this; but it would be consistent if the navigator could also be used to achieve the same displays that are possible via cursor scrolling. In the attached example, the lower part of the page cannot be made visible using the navigator.