DND an AnchorPane, then a Button.
Start inline edit the button (either content or hierarchy panel).

You get the following stack and the inline edit TextField remains :

at com.oracle.javafx.scenebuilder.kit.editor.panel.inspector.InspectorPanelController.editorSelectionDidChange(InspectorPanelController.java:488)
at com.oracle.javafx.scenebuilder.kit.editor.panel.util.AbstractPanelController$6.changed(AbstractPanelController.java:250)
at com.oracle.javafx.scenebuilder.kit.editor.panel.util.AbstractPanelController$6.changed(AbstractPanelController.java:245)
at com.sun.javafx.binding.ExpressionHelper$Generic.fireValueChangedEvent(ExpressionHelper.java:347)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:80)
at javafx.beans.property.IntegerPropertyBase.fireValueChangedEvent(IntegerPropertyBase.java:106)
at javafx.beans.property.IntegerPropertyBase.markInvalid(IntegerPropertyBase.java:113)
at javafx.beans.property.IntegerPropertyBase.set(IntegerPropertyBase.java:146)
at com.oracle.javafx.scenebuilder.kit.editor.selection.Selection.incrementRevision(Selection.java:532)
at com.oracle.javafx.scenebuilder.kit.editor.selection.Selection.endUpdate(Selection.java:480)
at com.oracle.javafx.scenebuilder.kit.editor.job.v2.CompositeJob.execute(CompositeJob.java:104)
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.panel.content.mode.EditModeController.inlineEditingDidRequestCommit(EditModeController.java:853)
at com.oracle.javafx.scenebuilder.kit.editor.panel.content.mode.EditModeController.access$900(EditModeController.java:96)
at com.oracle.javafx.scenebuilder.kit.editor.panel.content.mode.EditModeController$10.call(EditModeController.java:815)
at com.oracle.javafx.scenebuilder.kit.editor.panel.content.mode.EditModeController$10.call(EditModeController.java:812)
at com.oracle.javafx.scenebuilder.kit.editor.util.InlineEditController.requestCommitAndClose(InlineEditController.java:227)
at com.oracle.javafx.scenebuilder.kit.editor.util.InlineEditController.access$100(InlineEditController.java:64)
at com.oracle.javafx.scenebuilder.kit.editor.util.InlineEditController$1.handle(InlineEditController.java:181)
at com.oracle.javafx.scenebuilder.kit.editor.util.InlineEditController$1.handle(InlineEditController.java:171)
at com.sun.javafx.event.CompositeEventHandler$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.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
at javafx.stage.PopupWindow$PopupEventRedirector.handleKeyEvent(PopupWindow.java:985)
at javafx.stage.PopupWindow$PopupEventRedirector.handleRedirectedEvent(PopupWindow.java:958)
at com.sun.javafx.event.EventRedirector.dispatchCapturingEvent(EventRedirector.java:106)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchCapturingEvent(CompositeEventDispatcher.java:43)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:52)
at com.sun.javafx.event.EventRedirector.redirectEvent(EventRedirector.java:124)
at com.sun.javafx.event.EventRedirector.dispatchCapturingEvent(EventRedirector.java:103)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchCapturingEvent(CompositeEventDispatcher.java:43)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:52)
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$KeyHandler.process(Scene.java:3949)
at javafx.scene.Scene$KeyHandler.access$2100(Scene.java:3896)
at javafx.scene.Scene.impl_processKeyEvent(Scene.java:2036)
at javafx.scene.Scene$ScenePeerListener.keyEvent(Scene.java:2493)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$KeyEventNotification.run(GlassViewEventHandler.java:170)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$KeyEventNotification.run(GlassViewEventHandler.java:123)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleKeyEvent(GlassViewEventHandler.java:197)
at com.sun.glass.ui.View.handleKeyEvent(View.java:517)
at com.sun.glass.ui.View.notifyKey(View.java:927)