title: Flex editable combobox
body: <p>I am using editable combobox for my application. Combobox have default behavior like </p>
  
  <p>If I enter some text which is not similar to the combobox dataprovider values, combobox by default select first dataprovider value and close the dropdown window. I want stop this default behavior. </p>
  
  <p>Ex. I have combobox with the dataprovider value. (stack, stackoverflow, stackoverflow A)
  I open the dropdown and see the "stackoverflow A" value is in the dropdown. Now I enter value "stackoverflow B" but this value is not in the dropdown so when I enter, combobox override my entered text and replace "stackoverflow B" with first value of dataprovider(dropdown) "stack" and fire the selectedindex change event. I want to stop default behavior of combobox of selection of first value by default and look for entered value.  </p>
  
  <p>I have tried doing selectedindex to -1 by default but its still taking the first value by default. Any work around or suggestion would be helpful. </p>
  
  <p>thanks</p>