Fire onchange event when hidden input changes
<p>I have various inputs that I want to set a dirty flag.</p>

<p>However the onchange event does not fire if these inputs are modified by javascript.<br>
Many of the inputs are customised data entry moodules written by many other people and have hidden input and javascript UI layer to modify the hidden input.</p>

<p>I want to detect when these hidden inputs change. (without modifying the original author's script)<br>
Also normal inputs do not trigger the 'onchange' event until 'blur' but I could get round this with the onkeyup event.</p>
