Arduino IDE OPEN/SAVE problem in Ubuntu

Finally, Arduino UNO has arrived. I've downloaded IDE tool and tested some examples. But a serious problem appeared that gave me a headache! Open and Save feature stops with a Java NullPointer Exception!!!

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException: NullPointerException
at sun.awt.motif.MFileDialogPeer.setFont(Native Method)
at sun.awt.motif.MComponentPeer.initialize(MComponentPeer.java:182)
at sun.awt.motif.MComponentPeer.init(MComponentPeer.java:226)
at sun.awt.motif.MWindowPeer.init(MWindowPeer.java:103)
at sun.awt.motif.MDialogPeer.<init>(MDialogPeer.java:39)
at sun.awt.motif.MFileDialogPeer.<init>(MFileDialogPeer.java:24)
at sun.awt.motif.MToolkit.createFileDialog(MToolkit.java:263)
at java.awt.FileDialog.addNotify(FileDialog.java:265)
at java.awt.Dialog.conditionalShow(Dialog.java:887)
at java.awt.Dialog.show(Dialog.java:1035)
at java.awt.Component.show(Component.java:1584)
at java.awt.Component.setVisible(Component.java:1536)
at java.awt.Window.setVisible(Window.java:842)
at java.awt.Dialog.setVisible(Dialog.java:986)
at processing.app.Base.handleOpenPrompt(Base.java:649)
at processing.app.Base$3.actionPerformed(Base.java:906)

There was no answer even after some google searches. I was so disapointed that I setup Eclipse with AVR plugin to do my experiments. Examining the "AWT-EventQueue-0" error I looked for some environmental set relevant to AWT. I found that there was an AWT_TOOLKIT set. Unsetting this solved the problem!!!

$unset AWT_TOOLKIT
$arduino