FULL PRODUCT VERSION :
java version "1.8.0_40"
Java(TM) SE Runtime Environment (build 1.8.0_40-b27)
Java HotSpot(TM) 64-Bit Server VM (build 25.40-b25, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
OS X 10.9.5

A DESCRIPTION OF THE PROBLEM :
Characters being converted move unexpectedly by cursor keys that intended to select a candidate from the list.

I recorded a movie to show the problem: https://youtu.be/Rx18Cb8P5XI


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Launch the reproducer
2. Click somewhere in JTextArea
3. Turn on Input Method (Kotoeri) by hit CMD+SPACE
4. Enter some sentences and hit SPACE
5. Select a candidate from the list by cursor key (UP or DOWN)


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Characters being converted must not move by cursor keys during conversion.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
public class Main {

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            JFrame jFrame = new JFrame();
            JTextArea area = new JTextArea();
            jFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
            jFrame.setTitle("JTextArea test");
            jFrame.getContentPane().add(area);
            jFrame.setSize(600, 480);
            jFrame.setVisible(true);
        });
    }
}
---------- END SOURCE ----------