TreeTableView throws null pointers and essentially dies when you try to move a column, or hide a column.

Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
at com.sun.javafx.scene.control.skin.NestedTableColumnHeader.dispose(NestedTableColumnHeader.java:323)
at com.sun.javafx.scene.control.skin.NestedTableColumnHeader.updateTableColumnHeaders(NestedTableColumnHeader.java:265)
at com.sun.javafx.scene.control.skin.NestedTableColumnHeader.checkState(NestedTableColumnHeader.java:519)
at com.sun.javafx.scene.control.skin.NestedTableColumnHeader.computePrefHeight(NestedTableColumnHeader.java:401)
at javafx.scene.Parent.prefHeight(Parent.java:918)
at javafx.scene.layout.Region.prefHeight(Region.java:1438)
at com.sun.javafx.scene.control.skin.TableHeaderRow.computePrefHeight(TableHeaderRow.java:344)
at javafx.scene.Parent.prefHeight(Parent.java:918)
at javafx.scene.layout.Region.prefHeight(Region.java:1438)
at com.sun.javafx.scene.control.skin.TableViewSkinBase.layoutChildren(TableViewSkinBase.java:700)
at javafx.scene.control.Control.layoutChildren(Control.java:574)
at javafx.scene.control.TreeTableView.layoutChildren(TreeTableView.java:1348)
at javafx.scene.Parent.layout(Parent.java:1076)
at javafx.scene.Scene.doLayoutPass(Scene.java:568)
at javafx.scene.Scene$ScenePulseListener.pulse(Scene.java:2367)
at com.sun.javafx.tk.Toolkit.firePulse(Toolkit.java:330)
at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:479)
at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:460)
at com.sun.javafx.tk.quantum.QuantumToolkit$13.run(QuantumToolkit.java:327)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
at com.sun.glass.ui.gtk.GtkApplication.access$200(GtkApplication.java:48)
at com.sun.glass.ui.gtk.GtkApplication$6$1.run(GtkApplication.java:149)
at java.lang.Thread.run(Thread.java:744)