Bug 63769 Endless loop after Show in Package Explorer
there are situations when you run in an endless loop in show in package explorer when the action is attempting to reveal an element.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerPart.java
* the main type.  
	 */
	void expandMainType(Object element) {
		try {
			IType type= null;
			if (element instanceof ICompilationUnit) {
				ICompilationUnit cu= (ICompilationUnit)element;
				IType[] types= cu.getTypes();
				if (types.length > 0)
					type= types[0];
			}
			else if (element instanceof IClassFile) {
				IClassFile cf= (IClassFile)element;
				type= cf.getType();
			}			
			if (type != null) {
				final IType type2= type;
				Control ctrl= fViewer.getControl();
				if (ctrl != null && !ctrl.isDisposed()) {
					ctrl.getDisplay().asyncExec(new Runnable() {
						public void run() {
							Control ctrl2= fViewer.getControl();
							if (ctrl2 != null && !ctrl2.isDisposed()) 
								fViewer.expandToLevel(type2, 1);
						}
					}); 
				}
			}
		} catch(JavaModelException e) {