OS: Windows Vista with Japanese IME installed
JRE: 1.5.0_17 or 1.6.0_18

The customer's app listens to an InputMethodEvent on JTextField and it creates a JDialog window if it gets a TEXT_CHANGED event. After the dialog window is closed, strange preedit character remains persistently on the text field with an underline.

A simple test program which simulate customer's app can reproduce the issue (it is attached to this report).

How to reproduce:
   
1) Run test case.
   C:\> javac IMECandidate.java
   C:\> java IMECandidate
   "main" window will appear.

2) Turn IME on
   (enable Japanese input by selecting Input Mode Hiragana)

3) Press the 'a' key.
   A popup window will appear as response to the TEXT_CHANGED event.

4) Trun IME off (Input Mode Alphanumeric)
   while the Java popup window is still open.

5) Click 'OK' button on popup window.
   popup window will be closed.

Now, you will see a Japanese character corresponding to the 'a' key. It looks like a preedit character since it has an underline. But actually, IME status is OFF and you can't convert this character any more. Moreover, you can delete this strange preedit character, but it will appear again if any new keys are pressed.

This issue is NOT seen on Windows XP.

In Windows XP, preedit character at Step 5) remains editable.
That means, you can still convert that character, after returning from dialog (IME keeps ON regardless dialog's IME status change).
According to the customer this is expected behavior.

Please evaluate the issue, and provide fix if it is concluded as a defect.