Bug Info:
=========
Enter a string in text field with insert mode and it is not replacing the characters on existing text which has already in text field while compare with native text field.

Steps to Reproduce:
===================

1. Launch a java app which is having text field with some string.
2. Focus the text field and put caret at beginning position.
3. Press the insert key in keyboard.
4. Type some string.

Expected Result:
================
The entered string should be replace the existing characters in text field.

Actual Result:
==============
The entered string is appending with existing text.