[251836] ClearPlaceHolderJob needs to check if the viewer control is disposed

plugins/org.eclipse.jst.j2ee.navigator.ui/j2ee-navigator/org/eclipse/jst/j2ee/navigator/internal/ClearPlaceHolderJob.java

diff --git a/plugins/org.eclipse.jst.j2ee.navigator.ui/j2ee-navigator/org/eclipse/jst/j2ee/navigator/internal/ClearPlaceHolderJob.java b/plugins/org.eclipse.jst.j2ee.navigator.ui/j2ee-navigator/org/eclipse/jst/j2ee/navigator/internal/ClearPlaceHolderJob.java
index c1ff1c4..4f29b2b 100644
--- a/plugins/org.eclipse.jst.j2ee.navigator.ui/j2ee-navigator/org/eclipse/jst/j2ee/navigator/internal/ClearPlaceHolderJob.java
+++ b/plugins/org.eclipse.jst.j2ee.navigator.ui/j2ee-navigator/org/eclipse/jst/j2ee/navigator/internal/ClearPlaceHolderJob.java
@@ -36,11 +36,15 @@
 	public IStatus runInUIThread(IProgressMonitor monitor) {
 
 		try {
-			viewer.getControl().setRedraw(false);
-			viewer.remove(placeHolder);
-			viewer.add(parent, children);
+			if( !viewer.getControl().isDisposed() ){
+				viewer.getControl().setRedraw(false);
+				viewer.remove(placeHolder);
+				viewer.add(parent, children);
+			}
 		} finally {
-			viewer.getControl().setRedraw(true);
+			if( !viewer.getControl().isDisposed() ){
+				viewer.getControl().setRedraw(true);
+			}
 		}
 		return Status.OK_STATUS;
 	}