FULL PRODUCT VERSION :
Java: 1.6.0_02-ea; Java HotSpot(TM) Client VM 1.6.0_02-ea-b02

ADDITIONAL OS VERSION INFORMATION :
Linux version 2.6.20-15-generic running on i386;

EXTRA RELEVANT SYSTEM CONFIGURATION :
ubuntu 7.04, gnome 2.18.1.
i've found this issue while using NetBeans IDE Dev (Build 070627)

A DESCRIPTION OF THE PROBLEM :
Exception occurs when working with JComboBox in persistence.xml editor in netbeans. When combobox is expanded and mouse cursor is on some item, tooltip with infromation(about data source) appears. If you close this tooltip by pressing ESC, NPE exception is fired. Better info in stacktrace.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. install http://bits.netbeans.org/download/6.0/nightly/latest/ - standard
2. new project - web - web application
3. new file - persistence - persistence unit
4. expand data source combobox
5. move mouse cursor on some data source and wait for tooltip
6. press esc ( and move with mouse :) => NPE occurs

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
i would expect closing tooltip immediately.
ACTUAL -
tooltip is closed in few seconds and if you move with mouse cursor NPE is fired.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
java.lang.NullPointerException
        at javax.swing.ToolTipManager.mouseExited(ToolTipManager.java:504)
        at java.awt.Component.processMouseEvent(Component.java:6044)
        at java.awt.Component.processEvent(Component.java:5803)
        at java.awt.Container.processEvent(Container.java:2058)
        at java.awt.Window.processEvent(Window.java:1787)
        at java.awt.Component.dispatchEventImpl(Component.java:4410)
        at java.awt.Container.dispatchEventImpl(Container.java:2116)
        at java.awt.Window.dispatchEventImpl(Window.java:2429)
        at java.awt.Component.dispatchEvent(Component.java:4240)
[catch] at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)


REPRODUCIBILITY :
This bug can be reproduced often.
** This bug has been transferred to IssueZilla by bt->iz web application ** On 7/2/07 By bugbridge
 This bug is superceded by and tracked as this NetBeans IssueZilla item:
http://www.netbeans.org/issues/show_bug.cgi?id=108615