D&D a Treeview
Open CSS Analyzer
While in CSS picking mode select one of the TreeView Cells (i.e. .tree-view .virtual-flow .clipped-container .sheet .tree-cell:odd:empty)
Choose View > Show Sample Data - Bug - following exception is thrown:

java.lang.AssertionError
at com.oracle.javafx.scenebuilder.kit.editor.panel.content.mode.HitNodeChrome.layoutDecoration(HitNodeChrome.java:119)
at com.oracle.javafx.scenebuilder.kit.editor.panel.content.AbstractDecoration$3.changed(AbstractDecoration.java:238)
at com.oracle.javafx.scenebuilder.kit.editor.panel.content.AbstractDecoration$3.changed(AbstractDecoration.java:235)
at com.sun.javafx.binding.ExpressionHelper$SingleChange.fireValueChangedEvent(ExpressionHelper.java:176)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:80)
at javafx.scene.Node$LazyBoundsProperty.invalidate(Node.java:9009)
at javafx.scene.Node$MiscProperties.invalidateBoundsInParent(Node.java:6226)
at javafx.scene.Node.invalidateBoundsInParent(Node.java:3100)
at javafx.scene.Node.transformedBoundsChanged(Node.java:3788)
at javafx.scene.Node.localBoundsChanged(Node.java:3774)
at javafx.scene.Node.impl_geomChanged(Node.java:3760)
at javafx.scene.Parent$1.onChanged(Parent.java:350)
at com.sun.javafx.collections.TrackableObservableList$1.onChanged(TrackableObservableList.java:48)
at com.sun.javafx.collections.ListListenerHelper$Generic.fireValueChangedEvent(ListListenerHelper.java:315)
at com.sun.javafx.collections.ListListenerHelper.fireValueChangedEvent(ListListenerHelper.java:72)
at javafx.collections.ObservableListBase.fireChange(ObservableListBase.java:233)
at javafx.collections.ListChangeBuilder.commit(ListChangeBuilder.java:482)
at javafx.collections.ListChangeBuilder.endChange(ListChangeBuilder.java:541)
at javafx.collections.ObservableListBase.endChange(ObservableListBase.java:205)
at javafx.collections.ModifiableObservableListBase.setAll(ModifiableObservableListBase.java:90)
at com.sun.javafx.collections.VetoableListDecorator.setAll(VetoableListDecorator.java:116)
at com.sun.javafx.collections.VetoableListDecorator.setAll(VetoableListDecorator.java:110)
at com.sun.javafx.scene.control.skin.LabeledSkinBase.updateChildren(LabeledSkinBase.java:635)
at com.sun.javafx.scene.control.skin.TreeCellSkin.updateChildren(TreeCellSkin.java:198)
at com.sun.javafx.scene.control.skin.LabeledSkinBase.handleControlPropertyChanged(LabeledSkinBase.java:184)
at com.sun.javafx.scene.control.skin.TreeCellSkin.handleControlPropertyChanged(TreeCellSkin.java:126)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$2.call(BehaviorSkinBase.java:189)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$2.call(BehaviorSkinBase.java:187)
at com.sun.javafx.scene.control.MultiplePropertyChangeListenerHandler$1.changed(MultiplePropertyChangeListenerHandler.java:55)
at javafx.beans.value.WeakChangeListener.changed(WeakChangeListener.java:89)
at com.sun.javafx.binding.ExpressionHelper$SingleChange.fireValueChangedEvent(ExpressionHelper.java:176)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:80)
at javafx.beans.property.ObjectPropertyBase.fireValueChangedEvent(ObjectPropertyBase.java:105)
at javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:112)
at javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:145)
at javafx.css.StyleableObjectProperty.set(StyleableObjectProperty.java:82)
at javafx.beans.property.ObjectProperty.setValue(ObjectProperty.java:69)
at javafx.scene.control.Labeled.setGraphic(Labeled.java:429)
at com.sun.javafx.scene.control.skin.TreeViewSkin$13.updateDisplay(TreeViewSkin.java:304)
at com.sun.javafx.scene.control.skin.TreeViewSkin$13.updateItem(TreeViewSkin.java:340)
at javafx.scene.control.TreeCell.updateItem(TreeCell.java:519)
at javafx.scene.control.TreeCell.indexChanged(TreeCell.java:474)
at javafx.scene.control.IndexedCell.updateIndex(IndexedCell.java:115)
at com.sun.javafx.scene.control.skin.VirtualFlow.layoutChildren(VirtualFlow.java:876)
at javafx.scene.Parent.layout(Parent.java:1076)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Group.prefWidth(Group.java:177)
at javafx.scene.Group.minWidth(Group.java:211)
at javafx.scene.layout.Region.computeChildPrefAreaWidth(Region.java:1731)
at javafx.scene.layout.Region.getMaxAreaWidth(Region.java:2000)
at javafx.scene.layout.Region.computeMaxPrefAreaWidth(Region.java:1869)
at javafx.scene.layout.StackPane.computePrefWidth(StackPane.java:301)
at javafx.scene.Parent.prefWidth(Parent.java:904)
at javafx.scene.layout.Region.prefWidth(Region.java:1422)
at javafx.scene.layout.Region.minWidth(Region.java:1388)
at com.sun.javafx.scene.control.skin.ScrollPaneSkin.computeScrollNodeSize(ScrollPaneSkin.java:915)
at com.sun.javafx.scene.control.skin.ScrollPaneSkin.layoutChildren(ScrollPaneSkin.java:791)
at javafx.scene.control.Control.layoutChildren(Control.java:574)
at javafx.scene.Parent.layout(Parent.java:1076)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Parent.layout(Parent.java:1082)
at javafx.scene.Scene.doLayoutPass(Scene.java:576)
at javafx.scene.Scene$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)