FULL PRODUCT VERSION :
java version "1.6.0_17"
Java(TM) SE Runtime Environment (build 1.6.0_17-b04)
Java HotSpot(TM) Client VM (build 14.3-b01, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
ver XP

A DESCRIPTION OF THE PROBLEM :
The problem occurs if I switch between TextFields while I type something on the keyboard. I don't know exactly when the error occurs. I have to switch and type for a longer time, then the exception will be thrown.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
typing on the keyboard and switching between TextFields on the same time

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
the typed text in the TextField
ACTUAL -
Exception

ERROR MESSAGES/STACK TRACES THAT OCCUR :
--- Message: 7---
java.lang.ArrayIndexOutOfBoundsException: 7

at sun.font.FontDesignMetrics.charsWidth(FontDesignMetrics.java:492)
at javax.swing.text.Utilities.getTabbedTextOffset(Utilities.java:381)
at javax.swing.text.Utilities.getTabbedTextOffset(Utilities.java:302)
at javax.swing.text.Utilities.getTabbedTextOffset(Utilities.java:286)
at javax.swing.text.PlainView.viewToModel(PlainView.java:403)
at javax.swing.text.FieldView.viewToModel(FieldView.java:263)
at javax.swing.plaf.basic.BasicTextUI$RootView.viewToModel(BasicTextUI.java:1540)
at javax.swing.plaf.basic.BasicTextUI.viewToModel(BasicTextUI.java:1089)
at javax.swing.text.DefaultCaret.moveCaret(DefaultCaret.java:311)
at javax.swing.text.DefaultCaret.mouseDragged(DefaultCaret.java:565)
at java.awt.AWTEventMulticaster.mouseDragged(AWTEventMulticaster.java:303)
at java.awt.Component.processMouseMotionEvent(Component.java:6311)
at javax.swing.JComponent.processMouseMotionEvent(JComponent.java:3285)
at java.awt.Component.processEvent(Component.java:6032)
at java.awt.Container.processEvent(Container.java:2041)
at java.awt.Component.dispatchEventImpl(Component.java:4630)
at java.awt.Container.dispatchEventImpl(Container.java:2099)
at java.awt.Component.dispatchEvent(Component.java:4460)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4574)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4255)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4168)
at java.awt.Container.dispatchEventImpl(Container.java:2085)
at java.awt.Window.dispatchEventImpl(Window.java:2475)
at java.awt.Component.dispatchEvent(Component.java:4460)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)

REPRODUCIBILITY :
This bug can be reproduced always.