Adding a column form the inspector, one get the exception:

Warning: using SetPropertyAction to set an iterable property (javafx.scene.layout.GridPane.columnConstraints). Consider using AddItemToListAction or RemoveItemFromListAction instead.
SetPropertyAction(Element=Element[id=gridPane1], target=Grid hgap=0.0, vgap=0.0, alignment=TOP_LEFT, property=javafx.scene.layout.GridPane.columnConstraints) failed
java.lang.IllegalArgumentException: Failed to set javafx.scene.layout.GridPane.columnConstraints to [ColumnConstraints percentWidth=-1.0 minWidth=10.0 prefWidth=50.0 maxWidth=-1.0 hgrow=SOMETIMES fillWidth=true halignment=null, ColumnConstraints percentWidth=-1.0 minWidth=10.0 prefWidth=50.0 maxWidth=-1.0 hgrow=SOMETIMES fillWidth=true halignment=null, ColumnConstraints percentWidth=-1.0 minWidth=10.0 prefWidth=50.0 maxWidth=-1.0 hgrow=SOMETIMES fillWidth=true halignment=null, ColumnConstraints percentWidth=-1.0 minWidth=10.0 prefWidth=-1.0 maxWidth=-1.0 hgrow=null fillWidth=true halignment=null, ColumnConstraints percentWidth=-1.0 minWidth=10.0 prefWidth=50.0 maxWidth=-1.0 hgrow=SOMETIMES fillWidth=true halignment=null]
at com.oracle.javafx.authoring.persist.Prop$BeanProp.set(Prop.java:102)
at com.oracle.javafx.authoring.model.transactions.SetPropertyAction.apply(SetPropertyAction.java:111)
at com.oracle.javafx.authoring.model.transactions.Transaction.register(Transaction.java:95)
at com.oracle.javafx.authoring.model.transactions.Transaction.setProperty(Transaction.java:376)
at com.oracle.javafx.authoring.dictionary.definition.GridPaneComponentDefinition$Grid.add(GridPaneComponentDefinition.java:391)
at com.oracle.javafx.authoring.dictionary.definition.GridPaneComponentDefinition$Grid.addColumn(GridPaneComponentDefinition.java:721)
at com.oracle.javafx.authoring.dictionary.definition.GridPaneComponentDefinition$GridColumns.add(GridPaneComponentDefinition.java:970)
at com.oracle.javafx.authoring.presenters.valueeditors.SlotValueConstraintsBaseEditor$SlotConstraint.add(SlotValueConstraintsBaseEditor.java:122)
at com.oracle.javafx.authoring.presenters.valueeditors.SlotValueConstraintsBaseEditor$SlotConstraint.access$000(SlotValueConstraintsBaseEditor.java:90)
at com.oracle.javafx.authoring.presenters.valueeditors.SlotValueConstraintsBaseEditor$SlotConstraint$2.handle(SlotValueConstraintsBaseEditor.java:109)
at com.oracle.javafx.authoring.presenters.valueeditors.SlotValueConstraintsBaseEditor$SlotConstraint$2.handle(SlotValueConstraintsBaseEditor.java:106)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:69)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:162)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:115)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:28)
at javafx.event.Event.fireEvent(Event.java:171)
at javafx.scene.control.MenuItem.fire(MenuItem.java:387)
at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer.doSelect(ContextMenuContent.java:1117)
at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer$6.handle(ContextMenuContent.java:1080)
at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer$6.handle(ContextMenuContent.java:1078)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:69)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:162)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:115)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:33)
at javafx.event.Event.fireEvent(Event.java:171)
at javafx.scene.Scene$MouseHandler.process(Scene.java:2893)
at javafx.scene.Scene$MouseHandler.process(Scene.java:2687)
at javafx.scene.Scene$MouseHandler.access$1300(Scene.java:2653)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1279)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:1911)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:210)
at com.sun.glass.ui.View.handleMouseEvent(View.java:330)
at com.sun.glass.ui.View.notifyMouse(View.java:686)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.access$100(WinApplication.java:29)
at com.sun.glass.ui.win.WinApplication$2$1.run(WinApplication.java:62)
at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.ArrayIndexOutOfBoundsException: 4
at javafx.scene.layout.GridPaneDesignInfo.getCellBounds(GridPaneDesignInfo.java:85)
at com.oracle.javafx.authoring.stage.v2.handles.gridpane.GridPaneMosaic.addCellAndGaps(GridPaneMosaic.java:555)
at com.oracle.javafx.authoring.stage.v2.handles.gridpane.GridPaneMosaic.<init>(GridPaneMosaic.java:181)
at com.oracle.javafx.authoring.stage.v2.handles.gridpane.GridPaneSelectionHandles.createGridDividerChildren(GridPaneSelectionHandles.java:173)
at com.oracle.javafx.authoring.stage.v2.handles.gridpane.GridPaneSelectionHandles.createChildren(GridPaneSelectionHandles.java:149)
at com.oracle.javafx.authoring.stage.v2.handles.GenericSelectionHandles.targetLayoutDidChange(GenericSelectionHandles.java:49)
at com.oracle.javafx.authoring.stage.v2.handles.gridpane.GridPaneSelectionHandles.access$200(GridPaneSelectionHandles.java:23)
at com.oracle.javafx.authoring.stage.v2.handles.gridpane.GridPaneSelectionHandles$3.onChanged(GridPaneSelectionHandles.java:291)
at com.sun.javafx.collections.ObservableListWrapper.callObservers(ObservableListWrapper.java:78)
at com.sun.javafx.collections.TrackableObservableList.callObservers(TrackableObservableList.java:31)
at com.sun.javafx.collections.ObservableListWrapper.setAll(ObservableListWrapper.java:221)
at com.oracle.javafx.authoring.persist.Prop$BeanProp.set(Prop.java:100)
... 47 more