title: how to stop onChange in javascript
body: <p>in one of my selection box, i have a onChange="..." specified...
  coz i want to change some other form value after any selection changes.</p>
  
  <p>however ... in the same page, some wired case i have to manually set the value..
  so i have to use some javascript to set the value of the selection combox, but in this case, i don`t want that onChange event to be fired...</p>
  
  <p>how can i walk around it???</p>
  
  <p>Forgot to mention that i am actually using dijit.form.comboBox. 
  for normal HTML form comboBox, it won`t cause any issue.
  Only i use the dijit comboBox, and i try to set the value to some other value, dojo will trigger the onChange.</p>