open attached jmem.fxml
expand the configuration tab and select the GridPane (5 x 7)
start DND a node from the GridPane (second column).

Full stack :

java.lang.IllegalStateException: Bug in FXOMRefresher: FXML dumped in /var/folders/8h/rr0bg9gn6kqc9bsc5605590r0000gr/T/DTL-5996-1999953651428193498.fxml
at com.oracle.javafx.scenebuilder.kit.fxom.FXOMRefresher.refresh(FXOMRefresher.java:77)
at com.oracle.javafx.scenebuilder.kit.fxom.FXOMDocument.refreshSceneGraph(FXOMDocument.java:268)
at com.oracle.javafx.scenebuilder.kit.fxom.FXOMDocument.endUpdate(FXOMDocument.java:255)
at com.oracle.javafx.scenebuilder.kit.fxom.FXOMNodes.newDocument(FXOMNodes.java:249)
at com.oracle.javafx.scenebuilder.kit.fxom.FXOMArchive.<init>(FXOMArchive.java:56)
at com.oracle.javafx.scenebuilder.kit.metadata.util.ClipboardEncoder.makeEncoding(ClipboardEncoder.java:78)
at com.oracle.javafx.scenebuilder.kit.editor.drag.source.DocumentDragSource.makeClipboardContent(DocumentDragSource.java:194)
at com.oracle.javafx.scenebuilder.kit.editor.panel.content.gesture.mouse.SelectAndMoveGesture.mouseDragDetected(SelectAndMoveGesture.java:185)
at com.oracle.javafx.scenebuilder.kit.editor.panel.content.gesture.mouse.AbstractMouseDragGesture$1.handle(AbstractMouseDragGesture.java:84)
at com.oracle.javafx.scenebuilder.kit.editor.panel.content.gesture.mouse.AbstractMouseDragGesture$1.handle(AbstractMouseDragGesture.java:80)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
at javafx.event.Event.fireEvent(Event.java:204)
at javafx.scene.Scene$DnDGesture.fireEvent(Scene.java:2920)
at javafx.scene.Scene$DnDGesture.process(Scene.java:2999)
at javafx.scene.Scene$DnDGesture.access$8400(Scene.java:2896)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3762)
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)
Caused by: java.io.IOException: javafx.fxml.LoadException:
/Users/slionsp/tmp/FXML/jmem.fxml:10

at com.oracle.javafx.scenebuilder.kit.fxom.FXOMLoader.load(FXOMLoader.java:92)
at com.oracle.javafx.scenebuilder.kit.fxom.FXOMDocument.<init>(FXOMDocument.java:80)
at com.oracle.javafx.scenebuilder.kit.fxom.FXOMRefresher.refresh(FXOMRefresher.java:55)
... 43 more
Caused by: javafx.fxml.LoadException:
/Users/slionsp/tmp/FXML/jmem.fxml:10

at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2617)
at javafx.fxml.FXMLLoader.access$700(FXMLLoader.java:104)
at javafx.fxml.FXMLLoader$InstanceDeclarationElement.constructValue(FXMLLoader.java:1014)
at javafx.fxml.FXMLLoader$ValueElement.processStartElement(FXMLLoader.java:740)
at javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2723)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2527)
at javafx.fxml.FXMLLoader.load(FXMLLoader.java:2425)
at com.oracle.javafx.scenebuilder.kit.fxom.FXOMLoader.load(FXOMLoader.java:89)
... 45 more
Caused by: java.lang.IllegalAccessException: Class sun.reflect.misc.ReflectUtil can not access a member of class javafx.collections.FXCollections with modifiers "private"
at sun.reflect.Reflection.ensureMemberAccess(Reflection.java:101)
at java.lang.Class.newInstance(Class.java:427)
at sun.reflect.misc.ReflectUtil.newInstance(ReflectUtil.java:51)
at javafx.fxml.FXMLLoader$InstanceDeclarationElement.constructValue(FXMLLoader.java:1010)
... 50 more