Start SB App and work with the Untitled document.
Add Button to Content.
Delete Button.
Edit > Undo Delete Button
Edit > Undo Insert Button
Edit > Redo Insert Button
  --> the Button is not selected.
Edit > Redo Delete Button
  --> triggers following exception:

Exception in thread "JavaFX Application Thread" java.lang.AssertionError
at com.oracle.javafx.scenebuilder.kit.editor.job.DeleteObjectJob.redo(DeleteObjectJob.java:71)
at com.oracle.javafx.scenebuilder.kit.editor.job.DeleteSelectionJob.redo(DeleteSelectionJob.java:89)
at com.oracle.javafx.scenebuilder.kit.editor.JobManager.redoJob(JobManager.java:154)
at com.oracle.javafx.scenebuilder.kit.editor.JobManager.redo(JobManager.java:110)
at com.oracle.javafx.scenebuilder.kit.editor.EditorController.redo(EditorController.java:471)
at com.oracle.javafx.scenebuilder.app.menubar.MenuBarController$RedoActionController.perform(MenuBarController.java:774)
at com.oracle.javafx.scenebuilder.app.menubar.MenuBarController.handleOnActionMenu(MenuBarController.java:598)
at com.oracle.javafx.scenebuilder.app.menubar.MenuBarController.access$300(MenuBarController.java:48)
at com.oracle.javafx.scenebuilder.app.menubar.MenuBarController$8.handle(MenuBarController.java:591)
at com.oracle.javafx.scenebuilder.app.menubar.MenuBarController$8.handle(MenuBarController.java:587)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
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.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
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:49)
at javafx.event.Event.fireEvent(Event.java:203)
at javafx.scene.control.MenuItem.fire(MenuItem.java:462)
at com.sun.javafx.scene.control.GlobalMenuAdapter$5.handle(GlobalMenuAdapter.java:158)
at com.sun.javafx.scene.control.GlobalMenuAdapter$5.handle(GlobalMenuAdapter.java:156)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
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.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
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:203)
at javafx.scene.control.MenuItem.fire(MenuItem.java:462)
at com.sun.javafx.tk.quantum.GlassSystemMenu$6.action(GlassSystemMenu.java:234)