Event handlers don't work in Google Sites' HTMLBox

Google Sites allows people to use HTML and JavaScript and transforms it to be safe. It throws away dynamically-generated JavaScript, so the onclick and onchange handlers get stripped. If the event handler code was supplied beforehand and the generated HTML nodes were labeled with an attribute that told which event handler to apply, a pass over the static nodes could attach them and allow datepicker to work on Sites.

A CL on github is in preparation.