A manager can configure a block to display throughout the site

1. Login as a manager and turn editing on for the front page.
2. Add a comments block.
3. Configure the comments block and set the page contexts to display throughout the entire site.
4. Browse to a course and check that the comments block is displayed on the course page.
5. Configure the comments block on the course page and change the weight on this page to -10.
6. Check that the comments block is displayed at the top of the course page (or just below any other blocks with weight -10).