They come from a library called The Bayeux Tapestry Extensions.
To make the library available, we got the tapestry-bayeux.jar (see get-dependent-files in build.xml) and declared the library in jumpstart-max.application.
The "do it once" components use javascript and act together, so once one of them has been clicked all of them will ignore subsequent clicks
until a response has been received. Try clicking on them impatiently and you will see that only 1 order is placed.
Tapestry exceptions If you get an exception saying a property "has already been accounted for by the element
at Annotation" then restart JBoss with -Dorg.apache.tapestry.disable-caching=false before using this page.