java.lang.NullPointerException
        at org.netbeans.modules.uml.diagrams.nodes.OperationWidget.notifyFontChanged(OperationWidget.java:109)
        at org.netbeans.api.visual.widget.Widget.setFont(Widget.java:722)
        at org.netbeans.modules.uml.diagrams.nodes.UMLClassWidget.notifyFontChanged(UMLClassWidget.java:908)
        at org.netbeans.api.visual.widget.Widget.setFont(Widget.java:722)
        at org.netbeans.modules.uml.drawingarea.view.CustomizableNodeViewContainer.notifyFontChanged(CustomizableNodeViewContainer.java:71)
        at org.netbeans.api.visual.widget.Widget$3.propertyChange(Widget.java:761)
        at org.netbeans.api.visual.widget.ResourceTable.fireEventAndCleanList(ResourceTable.java:559)
        at org.netbeans.api.visual.widget.ResourceTable.firePropertyChange(ResourceTable.java:496)
        at org.netbeans.api.visual.widget.ResourceTable.notifyPropertyChanged(ResourceTable.java:589)
        at org.netbeans.api.visual.widget.ResourceTable.firePropertyChange(ResourceTable.java:505)
        at org.netbeans.api.visual.widget.ResourceTable.notifyPropertyChanged(ResourceTable.java:589)
        at org.netbeans.api.visual.widget.ResourceTable.firePropertyChange(ResourceTable.java:505)
        at org.netbeans.api.visual.widget.ResourceTable.firePropertyChange(ResourceTable.java:486)
        at org.netbeans.api.visual.widget.ResourceTable.addProperty(ResourceTable.java:220)
        at org.netbeans.modules.uml.drawingarea.view.ResourceValue.save(ResourceValue.java:122)
        at org.netbeans.modules.uml.drawingarea.view.ResourceValue.save(ResourceValue.java:109)
        at org.netbeans.modules.uml.diagrams.options.ElementCustomizationPanel.save(ElementCustomizationPanel.java:108)
        at org.netbeans.modules.uml.diagrams.options.ElementOptionsPanel.applyChanges(ElementOptionsPanel.java:74)
        at org.netbeans.modules.uml.propertysupport.options.UMLPanelController.applyChanges(UMLPanelController.java:102)
        at org.netbeans.modules.options.CategoryModel$Category.applyChanges(CategoryModel.java:389)
        at org.netbeans.modules.options.CategoryModel$Category.access$1000(CategoryModel.java:313)
        at org.netbeans.modules.options.CategoryModel.save(CategoryModel.java:215)
        at org.netbeans.modules.options.OptionsPanel.save(OptionsPanel.java:202)
        at org.netbeans.modules.options.OptionsDisplayerImpl$OptionsPanelListener.actionPerformed(OptionsDisplayerImpl.java:293)
        at org.netbeans.core.windows.services.NbPresenter$ButtonListener.actionPerformed(NbPresenter.java:1266)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
        at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
        at java.awt.Component.processMouseEvent(Component.java:6216)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3265)
        at java.awt.Component.processEvent(Component.java:5981)
        at java.awt.Container.processEvent(Container.java:2041)
        at java.awt.Component.dispatchEventImpl(Component.java:4583)
        at java.awt.Container.dispatchEventImpl(Container.java:2099)
        at java.awt.Component.dispatchEvent(Component.java:4413)
        at java.awt.LightweightDispatcher.retargetMouseEvent(LightweightDispatcher.java:4556)
        at java.awt.LightweightDispatcher.processMouseEvent(LightweightDispatcher.java:4220)
        at java.awt.LightweightDispatcher.dispatchEvent(LightweightDispatcher.java:4150)
        at java.awt.Container.dispatchEventImpl(Container.java:2085)
        at java.awt.Window.dispatchEventImpl(Window.java:2475)
        at java.awt.Component.dispatchEvent(Component.java:4413)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:104)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)