Navigator does not follow vertical orientation when vertical page orientation is selected

In current master and 2.0.3 nightlies, there is an option in the Canvas section of the Preferences to choose whether to display pages in a scrolling vertical column, or left-to-right horizontally (the default in 2.0.2).

If the vertical orientation is selected, the horizontal Navigator at the bottom of the window basically becomes useless—it displays only the first page, and nothing can make the rest of the score show. The Navigator should reposition to a vertical orientation accordingly, on either the left or right side of the window.