Cart widget appears when collections are added. It links to the Download tab

This pull request is the the first half of the requirements to show that the user has added some collections and to provide a link to Step 3

Next: add functionality to allow the removal of individual collections or clearing/reseting from the download cart.
Actually your right. 
This function is never called directly so the returning of false here is pointless. The function directly called by the onclick action has to return false. IE the jQuery