Event Firing in Prototype: A Reminder

document.observe("widget:frobbed", function(event) {
  console.log("Element with ID (" + event.target.id +
   ") frobbed widget #" + event.memo.widgetNumber + ".");
});

var someNode = $('foo');
someNode.fire("widget:frobbed", { widgetNumber: 19 });

//-> "Element with ID (foo) frobbed widget #19."

When attaching event handlers via Prototype, I've done the following
in the past...

Event.observe(window, 'load', function () {

});

...or stuff like...

Event.observe(element_to_observe, 'change',
event_handler_function_X );

...so try ...

var r = Raphael('plot',100,100);
var plot = r.rect(0,0,100,100);

Event.observe(plot, 'mousemove', function () {
    alert("Did it work?");

});