prototypejs - Programmatically manipulating DOM element value doesn't fire onchange event -

I have a hidden form field, and when the button is pressed, the value of the hidden field changes now, I have added a supervisor in the hidden area, listening to change, however, for some reason, the event listener never kicks, even if the value of the hidden element changes. I am using prototype and Firefox 3.6.

The code looks roughly like this:

  button.observe ('click', function (event) {hiddenField.setValue (some value);}); HiddenField.observe ('change', function (event) {warning ('this works!');});  

Is there any clue why the successor does not execute?

Thank you!

you

event needs fire ..

< Pre> button. Promotion ('click', function (event) {HiddenField.setValue (someValue); hiddenField.Simulate ('change');});

and then follow it:

  hiddenAffield .observe ('change', function (event) {warning ('this works!') ;});