The blue rectangle in the navigator should snap to page edges
When moving the blue rectangle in the navigator and the rectangle passes over the edge of a page, it should snap to, so it would be easier to align the edge with the limit of the score view (display area). It would be particularly useful when the zoom is "Page Width" because it would be very easy to exactly fit pages in the score view.
For example, say we have a score containing 3 pages and the zoom is set to "Page Width". When we move the blue rectangle, it's not easy to exactly fit the page 2. We must be very precise and do some trial and error to the left, to the right, to the left, to the right, etc.: