I was saving a pom.xml file and suddenly got an error message saying this:

org.eclipse.core.runtime.AssertionFailedException: null argument:The dialog should be created in UI thread
at org.eclipse.core.runtime.Assert.isNotNull(Assert.java:85)
at org.eclipse.jface.dialogs.IconAndMessageDialog.getSWTImage(IconAndMessageDialog.java:282)
at org.eclipse.jface.dialogs.IconAndMessageDialog.getQuestionImage(IconAndMessageDialog.java:260)
at org.eclipse.jface.dialogs.MessageDialog.<init>(MessageDialog.java:189)
at org.jboss.tools.common.model.ui.wizards.one.ServiceDialogImpl.showDialog(ServiceDialogImpl.java:62)
at org.jboss.tools.common.model.filesystems.impl.FolderImpl.question(FolderImpl.java:773)
at org.jboss.tools.common.model.filesystems.impl.FolderImpl.updateRemove(FolderImpl.java:724)
at org.jboss.tools.common.model.filesystems.impl.FolderImpl.update(FolderImpl.java:416)
at org.jboss.tools.common.model.filesystems.impl.FileSystemFolderLoader.update(FileSystemFolderLoader.java:28)
at org.jboss.tools.common.model.filesystems.impl.FileSystemsLoader.update(FileSystemsLoader.java:68)
at org.jboss.tools.common.model.filesystems.impl.FileSystemsImpl.doUpdate(FileSystemsImpl.java:343)
at org.jboss.tools.common.model.filesystems.impl.FileSystemsImpl.access$4(FileSystemsImpl.java:337)
at org.jboss.tools.common.model.filesystems.impl.FileSystemsImpl$UpdateRunnable.run(FileSystemsImpl.java:326)
at org.jboss.tools.common.model.XJob.runInWorkspace(XJob.java:178)
at org.eclipse.core.internal.resources.InternalWorkspaceJob.run(InternalWorkspaceJob.java:38)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:54)

So something went wrong - and I guess its trying to show an error dialog but its done from non-ui thread.