Open the attached Hierarchy-bad.fxml
Disclose the MenuButton - bug - hierarchy displays badly (see screenshot) and Exception is thrown:

SEVERE: An exception was thrown:
java.lang.NullPointerException
at com.oracle.javafx.scenebuilder.kit.metadata.util.DesignHierarchyMask.getDescription(DesignHierarchyMask.java:270)
at com.oracle.javafx.scenebuilder.kit.metadata.util.DesignHierarchyMask.getSingleLineDescription(DesignHierarchyMask.java:281)
at com.oracle.javafx.scenebuilder.kit.editor.panel.hierarchy.HierarchyItem.getSingleLineDescription(HierarchyItem.java:141)
at com.oracle.javafx.scenebuilder.kit.editor.panel.hierarchy.HierarchyItem.getDisplayInfo(HierarchyItem.java:177)
at com.oracle.javafx.scenebuilder.kit.editor.panel.hierarchy.treeview.HierarchyTreeCell.updateLayout(HierarchyTreeCell.java:770)
at com.oracle.javafx.scenebuilder.kit.editor.panel.hierarchy.treeview.HierarchyTreeCell.updateItem(HierarchyTreeCell.java:500)
at com.oracle.javafx.scenebuilder.kit.editor.panel.hierarchy.treeview.HierarchyTreeCell.updateItem(HierarchyTreeCell.java:107)
at javafx.scene.control.TreeCell.updateItem(TreeCell.java:509)
at javafx.scene.control.TreeCell.indexChanged(TreeCell.java:474)
at javafx.scene.control.IndexedCell.updateIndex(IndexedCell.java:115)
at com.sun.javafx.scene.control.skin.VirtualFlow.setCellIndex(VirtualFlow.java:1792)
at com.sun.javafx.scene.control.skin.VirtualFlow.addTrailingCells(VirtualFlow.java:1211)
at com.sun.javafx.scene.control.skin.VirtualFlow.layoutChildren(VirtualFlow.java:1102)
at com.sun.javafx.scene.control.skin.VirtualFlow.setCellCount(VirtualFlow.java:227)
at com.sun.javafx.scene.control.skin.TreeViewSkin.updateRowCount(TreeViewSkin.java:221)
at com.sun.javafx.scene.control.skin.VirtualContainerBase.checkState(VirtualContainerBase.java:116)
at com.sun.javafx.scene.control.skin.VirtualContainerBase.layoutChildren(VirtualContainerBase.java:111)
at com.sun.javafx.scene.control.skin.TreeViewSkin.layoutChildren(TreeViewSkin.java:356)
at javafx.scene.control.Control.layoutChildren(Control.java:574)
at javafx.scene.control.TreeView.layoutChildren(TreeView.java:845)
at javafx.scene.Parent.layout(Parent.java:1076)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Scene.doLayoutPass(Scene.java:576)
at javafx.scene.Scene$ScenePulseListener.pulse(Scene.java:2386)
at com.sun.javafx.tk.Toolkit$3.run(Toolkit.java:322)
at com.sun.javafx.tk.Toolkit$3.run(Toolkit.java:320)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.Toolkit.runPulse(Toolkit.java:320)
at com.sun.javafx.tk.Toolkit.firePulse(Toolkit.java:349)
at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:479)
at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:460)
at com.sun.javafx.tk.quantum.QuantumToolkit$13.run(QuantumToolkit.java:327)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)