java.lang.NullPointerException
        at org.netbeans.modules.uml.diagrams.options.ElementCustomizationPanel.prepareDisplay(ElementCustomizationPanel.java:370)
        at org.netbeans.modules.uml.diagrams.options.ElementCustomizationPanel.typeComboBoxItemStateChanged(ElementCustomizationPanel.java:348)
        at org.netbeans.modules.uml.diagrams.options.ElementCustomizationPanel.access$200(ElementCustomizationPanel.java:58)
        at org.netbeans.modules.uml.diagrams.options.ElementCustomizationPanel$2.itemStateChanged(ElementCustomizationPanel.java:222)
        at javax.swing.JComboBox.fireItemStateChanged(JComboBox.java:1205)
        at javax.swing.JComboBox.selectedItemChanged(JComboBox.java:1253)
        at javax.swing.JComboBox.contentsChanged(JComboBox.java:1309)
        at javax.swing.AbstractListModel.fireContentsChanged(AbstractListModel.java:100)
        at javax.swing.DefaultComboBoxModel.setSelectedItem(DefaultComboBoxModel.java:88)
        at javax.swing.JComboBox.setSelectedItem(JComboBox.java:557)
        at javax.swing.JComboBox.setSelectedIndex(JComboBox.java:599)
        at javax.swing.plaf.basic.BasicComboPopup$Handler.mouseReleased(BasicComboPopup.java:816)
        at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:273)
        at java.awt.Component.processMouseEvent(Component.java:6348)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)
        at javax.swing.plaf.basic.BasicComboPopup$1.processMouseEvent(BasicComboPopup.java:480)
        at java.awt.Component.processEvent(Component.java:6113)
        at java.awt.Container.processEvent(Container.java:2085)
        at java.awt.Component.dispatchEventImpl(Component.java:4714)
        at java.awt.Container.dispatchEventImpl(Container.java:2143)
        at java.awt.Component.dispatchEvent(Component.java:4544)
        at java.awt.LightweightDispatcher.retargetMouseEvent(LightweightDispatcher.java:4618)
        at java.awt.LightweightDispatcher.processMouseEvent(LightweightDispatcher.java:4282)
        at java.awt.LightweightDispatcher.dispatchEvent(LightweightDispatcher.java:4212)
        at java.awt.Container.dispatchEventImpl(Container.java:2129)
        at java.awt.Window.dispatchEventImpl(Window.java:2475)
        at java.awt.Component.dispatchEvent(Component.java:4544)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:635)
        at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:104)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:296)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:211)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:201)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:196)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:188)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)