fck support keydown event???

Now I want to listen a keydown event in order to detect whether editorarea's content is changed.....but I find FCKeditor does'nt support this event .
I don't kown whether I use it incorrectly..please help me..
following is my code:
<html:form action="/edit" method="post" onsubmit="return chknext()">
<html:hidden property="method" value="editInfo" />
<%fckEditor.setValue("");
out.println(fckEditor);
%>

<br />
<html:submit property="submit" value="下一步" style="width:100px; height:40px"></html:submit>
</html:form>

thank you......