Open html file in WTP HTML Editor and in JBoss Tools HTML Editor the same time. Edit html document in JBoss Tools Editor. See the stacktrace

!ENTRY org.eclipse.ui 4 0 2014-10-09 22:18:21.265
!MESSAGE Unhandled event loop exception
!STACK 0
org.eclipse.swt.SWTException: Failed to execute runnable (java.lang.NullPointerException)
at org.eclipse.swt.SWT.error(SWT.java:4441)
at org.eclipse.swt.SWT.error(SWT.java:4356)
at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:139)
at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:4147)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3764)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$9.run(PartRenderingEngine.java:1152)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1033)
at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:148)
at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:635)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:578)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:150)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:135)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:134)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:104)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:379)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:233)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:648)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:603)
at org.eclipse.equinox.launcher.Main.run(Main.java:1465)
at org.eclipse.equinox.launcher.Main.main(Main.java:1438)
Caused by: java.lang.NullPointerException
at org.jboss.tools.jst.web.ui.internal.editor.jspeditor.JSPTextEditor$1.run(JSPTextEditor.java:241)
at org.jboss.tools.jst.web.ui.internal.editor.jspeditor.JSPTextEditor.getPageContext(JSPTextEditor.java:253)
at org.jboss.tools.jst.web.ui.internal.editor.jspeditor.JSPTextEditor.updateModification(JSPTextEditor.java:469)
at org.jboss.tools.jst.web.ui.internal.editor.jspeditor.JSPMultiPageEditor.nodeChanged(JSPMultiPageEditor.java:782)
at org.jboss.tools.common.model.util.XModelTreeListenerSWTASync$R.run(XModelTreeListenerSWTASync.java:84)
at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35)
at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:136)
... 24 more