Dragging over NEWT Window occurs NullPointerException when drag back to the JTree component witch started the dragging event. Drag Start from JTree -> Drag Over to NEWT Window -> continue Drag Over again to JTree (NullPointerException occurs). java.lang.NullPointerException at javax.swing.TransferHandler$DropHandler.handleDrag(TransferHandler.java:1449) at javax.swing.TransferHandler$DropHandler.dragOver(TransferHandler.java:1488) at java.awt.dnd.DropTarget.dragOver(DropTarget.java:381) at javax.swing.TransferHandler$SwingDropTarget.dragOver(TransferHandler.java:1250) at sun.awt.dnd.SunDropTargetContextPeer.processMotionMessage(SunDropTargetContextPeer.java:474) at sun.awt.dnd.SunDropTargetContextPeer$EventDispatcher.dispatchMotionEvent(SunDropTargetContextPeer.java:823) at sun.awt.dnd.SunDropTargetContextPeer$EventDispatcher.dispatchEvent(SunDropTargetContextPeer.java:769) at sun.awt.dnd.SunDropTargetEvent.dispatch(SunDropTargetEvent.java:48) at java.awt.Component.dispatchEventImpl(Component.java:4716) at java.awt.Container.dispatchEventImpl(Container.java:2287) at java.awt.Component.dispatchEvent(Component.java:4687) at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832) at java.awt.LightweightDispatcher.processDropTargetEvent(Container.java:4566) at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4417) at java.awt.Container.dispatchEventImpl(Container.java:2273) at java.awt.Window.dispatchEventImpl(Window.java:2719) at java.awt.Component.dispatchEvent(Component.java:4687) at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:729) at java.awt.EventQueue.access$200(EventQueue.java:103) at java.awt.EventQueue$3.run(EventQueue.java:688) at java.awt.EventQueue$3.run(EventQueue.java:686) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87) at java.awt.EventQueue$4.run(EventQueue.java:702) at java.awt.EventQueue$4.run(EventQueue.java:700) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76) at java.awt.EventQueue.dispatchEvent(EventQueue.java:699) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138) at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
The shown stack trace only includes Swing classes, NEWT does not seem to be involved. Please provide a small test case / application for reproduction. Also add the platform information as requested and described in Wiki/FAQ/Bugreport, thank you.