If you hover over the Group mode icon to the right of the edit menu next to an activity while editing a course, you will not get a tool tip (title/alt text) message.

This effects 2.9, but not 2.8 and below. It was caused by MDL-50084.

In this case, the title text is included with the link tag that surrounds the image, but the image contains an empty title tag, which "overrides" the links title tag.

To explain - the old html_writer system would exclude attributes entirely if they were null. The new mustache system treats them as valueless attributes (eg <img title scr="...").

The old way made up have silly things like checked="checked", even though boolean attributes are perfectly valid. So it is generally better for us to have this ability - although I do wonder if there are various places where we may have quietly broken other things with the change in behavior.