We have also modified the course overview function to display a button which performs a click to hide/click to reveal on the box around the course data. The hiding and revealing of the section is done by using the standard JavaScript function elementToggleHide, in much the same way as is done for the content of blocks (see moodleblock.class.php). Please see the lower frame of the screenshot, in which the course "Parliament and the law" has now been hidden, but can be revealed by clicking on the "+" button at the left hand side.

If the user does not have JavaScript enabled on their browser, the sections will all be displayed by default, and the button will not work, but they will not see an obtrusive error if they click the button.

Note that Ray Lawrence has requested a config option to remove the ability to collapse sections, for consistency with blocks functionality.