title: move cursor spark text input
body: <p>I am using flex 4.5
  I am using spark.components.TextInput control.
  The values of the text can be change dynamically according to user selection.
  The problem is that after the user is write anythings the textInput and change the value of the text the cursor position return to the begining of the textInput so if the user wants to continue enter .text in textInput he first need to move the cursor to the end.</p>
  
  <p>How can I control the cursor position ?</p>
  
  <p>Thanks</p>