The Ext.form.ComboBox can be used to support autocomplete - choices either form local or
remote data store that prefill a list under the edit area as you type.
But it seems it always start to do so after at least 4 characters are typed in.
The doc on Ext.form.ComboBox does not list any property to change this.
So, how can one start the autocomplete upon first character?
See example: http://www.sencha.com/deploy/dev/examples/form/forum-search.html