Open attached FXML
Select the Button
Click in the Style Class textField so the auto-suggest menu appears
Click to select one of the style classes from the auto-suggest menu
Click in the Style property TextField - BUG - following exception occurs:

Aug 19, 2014 11:47:23 AM com.oracle.javafx.scenebuilder.app.SceneBuilderApp$SceneBuilderUncaughtExceptionHandler uncaughtException
SEVERE: An exception was thrown:
java.lang.NullPointerException
at com.sun.javafx.Utils.positionX(Utils.java:564)
at com.sun.javafx.Utils.pointRelativeTo(Utils.java:462)
at javafx.scene.control.ContextMenu.show(ContextMenu.java:258)
at com.oracle.javafx.scenebuilder.kit.editor.panel.inspector.editors.AutoSuggestEditor.showPopup(AutoSuggestEditor.java:327)
at com.oracle.javafx.scenebuilder.kit.editor.panel.inspector.editors.AutoSuggestEditor.handleSuggestedPopup(AutoSuggestEditor.java:293)
at com.oracle.javafx.scenebuilder.kit.editor.panel.inspector.editors.AutoSuggestEditor.lambda$initialize$135(AutoSuggestEditor.java:144)
at com.oracle.javafx.scenebuilder.kit.editor.panel.inspector.editors.AutoSuggestEditor$$Lambda$197/188266297.changed(Unknown Source)
at com.sun.javafx.binding.ExpressionHelper$Generic.fireValueChangedEvent(ExpressionHelper.java:361)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)
at javafx.beans.property.ReadOnlyBooleanPropertyBase.fireValueChangedEvent(ReadOnlyBooleanPropertyBase.java:72)
at javafx.scene.Node$FocusedProperty.notifyListeners(Node.java:7524)
at javafx.scene.Scene$13.invalidated(Scene.java:2039)
at javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:111)
at javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:145)
at javafx.scene.Scene$KeyHandler.setFocusOwner(Scene.java:3884)
at javafx.scene.Scene$KeyHandler.requestFocus(Scene.java:3931)
at javafx.scene.Scene$KeyHandler.access$1900(Scene.java:3870)
at javafx.scene.Scene.requestFocus(Scene.java:2003)
at javafx.scene.Node.requestFocus(Node.java:7685)
at com.sun.javafx.scene.control.behavior.TextFieldBehavior.mousePressed(TextFieldBehavior.java:238)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:95)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89)
at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
at javafx.event.Event.fireEvent(Event.java:198)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3717)
at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3445)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1721)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2454)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:348)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:273)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:382)
at com.sun.glass.ui.View.handleMouseEvent(View.java:549)
at com.sun.glass.ui.View.notifyMouse(View.java:921)