When launch Java2Demo in the linux machine with -Dsun.java2d.xrender=true option, it threw exceptions as below, however the exceptions are not always threw, I tried three times, only the first time it threw this exceptions, file a bug for record to track.

Java Version: 1.7.0-ea-b103
System info:
host name:jfcsqe-solar.sfbay.sun.com
Linux jfcsqe-solar 2.6.18-194.8.1.0.1.el5 #1 SMP Thu Jul 1 17:09:06 EDT 2010
i686 i686 i386 GNU/Linux
Red Hat Enterprise Linux Server release 5.5 (Tikanga)

How to produce the problem:
1, login to this machine
2, cd /export/jdk/jdk1.7.0 (b103 installed)
3, bin/java -jar -Dsun.java2d.xrender=true demo/jfc/Java2D/*.jar
4, click auto run, it threw exceptions during the run, but not always reproducible.

Exceptions as below:
bin/java -jar -Dsun.java2d.xrender=true demo/jfc/Java2D/*.jar

Java2D Demo RunWindow : 20 Runs, 10 second delay between tabs
java version: 1.7.0-ea
Linux 2.6.18-194.8.1.0.1.el5

#0 Tue Aug 03 16:46:35 PDT 2010, 8055.1406K used
ERROR invokeAndWait : java.lang.reflect.InvocationTargetException
java.lang.reflect.InvocationTargetException
        at java.awt.EventQueue.invokeAndWait(EventQueue.java:1162)
        at javax.swing.SwingUtilities.invokeAndWait(SwingUtilities.java:1346)
        at java2d.RunWindow.invokeAndWait(RunWindow.java:321)
        at java2d.RunWindow.run(RunWindow.java:236)
        at java.lang.Thread.run(Thread.java:717)
Caused by: sun.awt.X11.XException: Cannot write XdndAware property
        at sun.awt.X11.XDnDDropTargetProtocol.registerDropTarget(XDnDDropTargetProtocol.java:97)
        at sun.awt.X11.XDropTargetRegistry.registerDropSite(XDropTargetRegistry.java:571)
        at sun.awt.X11.XWindowPeer.addDropTarget(XWindowPeer.java:1902)
        at sun.awt.X11.XComponentPeer.addDropTarget(XComponentPeer.java:1352)
        at java.awt.dnd.DropTarget.addNotify(DropTarget.java:509)
        at java.awt.Component.addNotify(Component.java:6842)
        at java.awt.Container.addNotify(Container.java:2731)
        at javax.swing.JComponent.addNotify(JComponent.java:4741)
        at java.awt.Container.addNotify(Container.java:2742)
        at javax.swing.JComponent.addNotify(JComponent.java:4741)
        at java.awt.Container.addNotify(Container.java:2742)
        at javax.swing.JComponent.addNotify(JComponent.java:4741)
        at java.awt.Container.addNotify(Container.java:2742)
        at javax.swing.JComponent.addNotify(JComponent.java:4741)
        at java.awt.Container.addNotify(Container.java:2742)
        at javax.swing.JComponent.addNotify(JComponent.java:4741)
        at java.awt.Container.addImpl(Container.java:1102)
        at java.awt.Container.add(Container.java:398)
        at java2d.GlobalPanel.stateChanged(GlobalPanel.java:100)
        at javax.swing.JTabbedPane.fireStateChanged(JTabbedPane.java:416)
        at javax.swing.JTabbedPane$ModelListener.stateChanged(JTabbedPane.java:270)
        at javax.swing.DefaultSingleSelectionModel.fireStateChanged(DefaultSingleSelectionModel.java:132)
        at javax.swing.DefaultSingleSelectionModel.setSelectedIndex(DefaultSingleSelectionModel.java:67)
        at javax.swing.JTabbedPane.setSelectedIndexImpl(JTabbedPane.java:616)
        at javax.swing.JTabbedPane.setSelectedIndex(JTabbedPane.java:591)
        at java2d.RunWindow$3.run(RunWindow.java:233)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:241)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:660)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:209)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:118)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)
#1 Tue Aug 03 16:48:51 PDT 2010, 7577.7266K used