title: Issue on dojo onlick event on html button
body: <p>I am a new kid with dojo, I got weird issue which I take lots of time and have not yet found out, assume I have 4 buttons:</p>
  
  <pre><code>&lt;button id="btnMoveFirst" data-dojo-type="dijit.form.Button" iconclass="plusIcon"&gt;
      &amp;lt; &amp;lt;&lt;/button&gt;
  &lt;button id="btnMovePrev" data-dojo-type="dijit.form.Button" iconclass="plusIcon"&gt;
      &amp;lt;&lt;/button&gt;
  &lt;button id="btnMoveNext" data-dojo-type="dijit.form.Button" iconclass="plusIcon"&gt;
      &amp;gt;&lt;/button&gt;
  &lt;button id="btnMoveLast" data-dojo-type="dijit.form.Button" iconclass="plusIcon"&gt;
      &amp;gt; &amp;gt;&lt;/button&gt;
  </code></pre>
  
  <p>And use dojo with event <em>onclick</em> as below:</p>
  
  <pre><code>dojo.connect(dijit.registry.byId('btnMoveFirst'), "onclick",  function(evt){
      alert('test1');
  });
  
  dojo.connect(dijit.registry.byId('btnMovePrev'), "onclick",  function(evt){
       alert('test2');
  });
  
  dojo.connect(dijit.registry.byId('btnMoveNext'), "onclick",  function(evt){
       alert('test3');
  });
  
  dojo.connect(dijit.registry.byId('btnMoveLast'), "onclick",  function(evt){
       alert('test4');
  });
  </code></pre>
  
  <p>But when I click any one of 4 buttons, or even any button in form, I got 4 alerts instead of only correct one.</p>
  
  <p>Does anyone know this?</p>