Bug 123424 browsing perspective does not show some packages in hierarchical mode
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/browsing/PackagesViewHierarchicalContentProvider.java
private void postAdd(final Object child, final Object parent) {
		postRunnable(new Runnable() {
			public void run() {
				Control ctrl = fViewer.getControl();
				if (ctrl != null && !ctrl.isDisposed()) {
					((TreeViewer)fViewer).add(parent, child);
				}
			}
		});
	}
	private void postRemove(final Object object) {
		postRunnable(new Runnable() {
			public void run() {
				Control ctrl = fViewer.getControl();
				if (ctrl != null && !ctrl.isDisposed()) {
					((TreeViewer)fViewer).remove(object);
				}
			}
		});
	}
	private void postRefresh(final Object object) {
		postRunnable(new Runnable() {
			public void run() {
				Control ctrl= fViewer.getControl();
				if (ctrl != null && !ctrl.isDisposed()) {
					((TreeViewer) fViewer).refresh(object);
				}
			}
		});
	}