Thanks i was able to resolve the issue, I just need to add some styling so that it resonates with a standard combo-box.
Also i have this interesting query, I was sending a standard Post 'HTTP' request through a standard submit form rather than AJAX. So as its a standard form submit, I would like to handle the response,
for all correct scenarios, it is well handled by browser i.e. download of a file, but in case of a Server error, how can ExtJs handle this response ?? i just need to save that error message from server.