Drop a TreeTableColumn
From the Hierarchy, try to wrap it in an AnchorPane.
This has no effect, and the following assertion is thrown:

Exception in thread "JavaFX Application Thread" java.lang.AssertionError
at com.oracle.javafx.scenebuilder.kit.editor.job.wrap.WrapJobUtils.getUnionOfBounds(WrapJobUtils.java:235)
at com.oracle.javafx.scenebuilder.kit.editor.job.wrap.AbstractWrapInJob.modifyChildrenLayoutJobs(AbstractWrapInJob.java:319)
at com.oracle.javafx.scenebuilder.kit.editor.job.wrap.WrapInAnchorPaneJob.modifyChildrenJobs(WrapInAnchorPaneJob.java:56)
at com.oracle.javafx.scenebuilder.kit.editor.job.wrap.AbstractWrapInSubComponentJob.wrapInJobs(AbstractWrapInSubComponentJob.java:72)
at com.oracle.javafx.scenebuilder.kit.editor.job.wrap.AbstractWrapInJob.buildSubJobs(AbstractWrapInJob.java:249)
at com.oracle.javafx.scenebuilder.kit.editor.job.wrap.AbstractWrapInJob.execute(AbstractWrapInJob.java:122)
at com.oracle.javafx.scenebuilder.kit.editor.JobManager.executeJob(JobManager.java:181)
at com.oracle.javafx.scenebuilder.kit.editor.JobManager.push(JobManager.java:70)
at com.oracle.javafx.scenebuilder.kit.editor.EditorController.performWrap(EditorController.java:1532)
at com.oracle.javafx.scenebuilder.kit.editor.EditorController.performEditAction(EditorController.java:940)
at com.oracle.javafx.scenebuilder.kit.editor.util.ContextMenuController$EditActionController.perform(ContextMenuController.java:513)
at com.oracle.javafx.scenebuilder.kit.editor.util.ContextMenuController.handleOnActionMenu(ContextMenuController.java:252)
at com.oracle.javafx.scenebuilder.kit.editor.util.ContextMenuController.access$100(ContextMenuController.java:60)
at com.oracle.javafx.scenebuilder.kit.editor.util.ContextMenuController$3.handle(ContextMenuController.java:133)
at com.oracle.javafx.scenebuilder.kit.editor.util.ContextMenuController$3.handle(ContextMenuController.java:129)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
at javafx.event.Event.fireEvent(Event.java:204)
at javafx.scene.control.MenuItem.fire(MenuItem.java:462)
at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer.doSelect(ContextMenuContent.java:1344)
at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer.doSelect(ContextMenuContent.java:1319)
at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer$7.handle(ContextMenuContent.java:1287)
at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer$7.handle(ContextMenuContent.java:1285)
at com.sun.javafx.event.CompositeEventHandler$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.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
at javafx.event.Event.fireEvent(Event.java:204)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3746)
at javafx.scene.Scene$MouseHandler.access$1800(Scene.java:3471)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1695)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2486)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:314)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:243)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:345)
at com.sun.glass.ui.View.handleMouseEvent(View.java:526)
at com.sun.glass.ui.View.notifyMouse(View.java:898)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.access$300(WinApplication.java:39)
at com.sun.glass.ui.win.WinApplication$4$1.run(WinApplication.java:112)
at java.lang.Thread.run(Thread.java:744)