If we have many course categories, levels on course categories hierachy or both the list display in the combo will not be optimal. Each level of categories will be separated with a "/" and if we have many levels or just categories with a long name it's possible to not see all informations. That's not very practical  for the selection.

This bug is present when we edit/create a course and also if we want to create a new course category in the selection of the parent category.