java.lang.AssertionError: CloneableEditorSupport.getOpenedPanes() must be called from AWT thread only
   at org.openide.text.CloneableEditorSupport.getOpenedPanes(CloneableEditorSupport.java:1230)
   at org.netbeans.modules.xml.text.navigator.NavigatorContent.navigate(NavigatorContent.java:141)
   at org.netbeans.modules.xml.text.navigator.base.AbstractXMLNavigatorPanel.navigate(AbstractXMLNavigatorPanel.java:115)
   at org.netbeans.modules.xml.text.navigator.base.AbstractXMLNavigatorPanel$1.resultChanged(AbstractXMLNavigatorPanel.java:69)
   at org.openide.util.lookup.ProxyLookup$1Notify.run(ProxyLookup.java:181)
   at org.openide.util.lookup.ProxyLookup.setLookups(ProxyLookup.java:190)
   at org.openide.util.lookup.ProxyLookup.setLookups(ProxyLookup.java:126)
   at org.netbeans.modules.navigator.NavigatorController$ClientsLookup.beforeLookup(NavigatorController.java:972)
   at org.openide.util.lookup.ProxyLookup.lookup(ProxyLookup.java:215)
   at org.netbeans.modules.navigator.NavigatorController.findMimeForContext(NavigatorController.java:793)
   at org.netbeans.modules.navigator.NavigatorController.access$300(NavigatorController.java:101)
   at org.netbeans.modules.navigator.NavigatorController$1.run(NavigatorController.java:412)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1432)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2042)
Caused: org.openide.util.RequestProcessor$SlowItem: task failed due to: java.lang.AssertionError: CloneableEditorSupport.getOpenedPanes() must be called from AWT thread only
   at org.openide.util.RequestProcessor.post(RequestProcessor.java:424)
   at org.netbeans.modules.navigator.NavigatorController.updateContext(NavigatorController.java:408)
   at org.netbeans.modules.navigator.NavigatorController.access$800(NavigatorController.java:101)
   at org.netbeans.modules.navigator.NavigatorController$3.run(NavigatorController.java:742)
   at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:727)
   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(AccessController.java:0)
   at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:697)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:159)
   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)