While testing patch for DTL-6670, I encounter another issue.
Code base is SB 2.0 b20 + patch from http://sqe-rb.us.oracle.com/r/21436/

Steps to reproduce :
- clean user custom library
- start tool with assertions enabled
- import UnlockCustom.jar to Library
- DND Keypad from Library to Content panel
- DND just added Keypad from Content back to Library panel (this step does not fail due to applied patch)
- open a new document and DND second added Keypad_1 on Content or Hierarchy

You will get the assertion error below.


java.lang.AssertionError
at com.oracle.javafx.scenebuilder.kit.editor.job.ModifyFxControllerJob.<init>(ModifyFxControllerJob.java:52)
at com.oracle.javafx.scenebuilder.app.info.InfoPanelController.updateController(InfoPanelController.java:271)
at com.oracle.javafx.scenebuilder.app.info.InfoPanelController.updateController(InfoPanelController.java:253)
at com.oracle.javafx.scenebuilder.app.info.InfoPanelController.jobManagerRevisionDidChange(InfoPanelController.java:130)
at com.oracle.javafx.scenebuilder.kit.editor.panel.util.AbstractPanelController$5.changed(AbstractPanelController.java:237)
at com.oracle.javafx.scenebuilder.kit.editor.panel.util.AbstractPanelController$5.changed(AbstractPanelController.java:233)
at com.sun.javafx.binding.ExpressionHelper$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.JobManager.incrementRevision(JobManager.java:221)
at com.oracle.javafx.scenebuilder.kit.editor.JobManager.push(JobManager.java:86)
at com.oracle.javafx.scenebuilder.kit.editor.drag.DragController.end(DragController.java:126)
at com.oracle.javafx.scenebuilder.kit.editor.panel.library.LibraryPanelController$8.handle(LibraryPanelController.java:668)
at com.oracle.javafx.scenebuilder.kit.editor.panel.library.LibraryPanelController$8.handle(LibraryPanelController.java:663)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
at javafx.event.Event.fireEvent(Event.java:204)
at javafx.scene.Scene$DnDGesture.processDropEnd(Scene.java:3062)
at javafx.scene.Scene$DnDGesture.access$6800(Scene.java:2896)
at javafx.scene.Scene$DragSourceListener.dragDropEnd(Scene.java:3306)
at com.sun.javafx.tk.quantum.GlassSceneDnDEventHandler$6.run(GlassSceneDnDEventHandler.java:150)
at com.sun.javafx.tk.quantum.GlassSceneDnDEventHandler$6.run(GlassSceneDnDEventHandler.java:145)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassSceneDnDEventHandler.handleDragEnd(GlassSceneDnDEventHandler.java:145)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleDragEnd(GlassViewEventHandler.java:615)
at com.sun.glass.ui.View.handleDragEnd(View.java:652)
at com.sun.glass.ui.View.notifyDragEnd(View.java:966)
at com.sun.glass.ui.mac.MacPasteboard._putItemsFromArray(Native Method)
at com.sun.glass.ui.mac.MacPasteboard.putItemsFromArray(MacPasteboard.java:143)
at com.sun.glass.ui.mac.MacPasteboard.putItems(MacPasteboard.java:165)
at com.sun.glass.ui.mac.MacSystemClipboard.pushToSystem(MacSystemClipboard.java:223)
at com.sun.glass.ui.SystemClipboard.flush(SystemClipboard.java:51)
at com.sun.glass.ui.ClipboardAssistance.flush(ClipboardAssistance.java:59)
at com.sun.javafx.tk.quantum.QuantumClipboard.flush(QuantumClipboard.java:274)
at com.sun.javafx.tk.quantum.QuantumToolkit.startDrag(QuantumToolkit.java:1150)
at javafx.scene.Scene$DnDGesture.dragDetectedProcessed(Scene.java:2940)
at javafx.scene.Scene$DnDGesture.process(Scene.java:3009)
at javafx.scene.Scene$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)