Justin’s posterous

The onchange event can be attached (inline or as an event handler) to any form element. It fires whenever the value of the form field changes. Unfortunately, the behavior is a bit strange in IE, in that for a checkbox, or a radio button field, the event doesn't fire when it is supposed to (right when you click the option you want to choose), but instead it only fires, when you click elsewhere on the page/form, or if you explicitly call blur(); on the field.

Apparently this bug still exists in IE7 and IE8.