Note: Do the tests below for various browsers such as IE, Edge, Chrome, Firefox, Safari. Create a course. Enrol a student. Create an assignment. On the assignment's Submission types, tick File submissions Login as a student. Submit a PDF file with a few pages for the assignment. Login as a teacher and grade the student's assignment. On the assignment's grading page, check out the PDF editor (in 3.0, you need to click Launch PDF editor... ) Click on the next button (right arrow) of the PDF editor's page navigation. Confirm that the page changes to the next page. Confirm that the currently selected page label in the page selector is set to something like Page X of Y , where X corresponds to the currently selected page and Y corresponds to the PDF's total number of pages. Do the same test for the previous button (left arrow). Click on the page selector and select another page. Confirm that the page changes into the selected page. Click the previous or the next button. Confirm that the page changes to the appropriate previous or next page. Confirm that the currently selected page label in the page selector corresponds to the currently previous or the next page.