In course/lib.php on line 1716, the alt and title attributes can cause invalid HTML to be output because format_string() does not do anything to fix apostrophes in the text. The invalid HTML is occasionally causing layout glitches as a result. There are a number of simple obvious ways to fix it.

Replication steps:

1. Log in as admin
2. Navigate to Settings > Site admin > Advanced features
3. Enable completion tracking
4. Navigate to a course
5. Edit the course settings
6. Set Completion tracking setting to Enabled...
7. Create an activity and put an apostrophe (') in its name.
8. Save the activity and return to the course page
9. Mouse over the completion icon and note the tooltip