Make the entire Heading Expandable/Collapsible#406

Right now, when we create an expandable/collapsible heading, it only works when a user clicks on the arrow. Users generally click on the entire heading to expand and when it does not work, they report the issue saying that it is not working. This is because they assume that the entire heading along with the arrow is expandable/collapsible.

I think this feature should be enhanced to avoid the confusion and bug reporting. Thanks!