Many school users find the icons for activities and block menus unintuitive as they can't click them - there is not a link surrouding the images in the html.
This patch adds a new variable $CFG->clickable_icons, which allows many of the unclickable icons to be clickable - whilst allowing the previous behaviour to be kept.
When $CFG->clickable_icons is switched on, course activity icons are clickable, as are the course category icons in the all courses. As well as all block items which are links with icons.
Enabiling activity icons and course categories to be clickable is a fairly simple change to the code which displays them.
In order to make block links have clickable icons the code is slightly more hacky - if clickable icons are switched on a regular expression checks each block item with an icon to see if it starts with a link, extracts the link tag and puts it around the icon. I am not really sure if this could be done better with the way that moodle currently displays block items.