Bug 30751 [Viewers] Closing all projects doesnt clear package browser list [browsing]
In the java browsing perspective, if you close all projects, the packages browser still has a list of all the packages from the last opened project.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/StructuredViewer.java
*    did not take</li>
 *  <li>calls <code>postUpdateHook</code></li>
 * </ul>
 * </p>
 *
 * @param updateCode the code to run
 */
protected void preservingSelection(Runnable updateCode) {
	
	ISelection oldSelection= null;
	try {
		
		oldSelection= getSelection();
		inChange= restoreSelection= true;
		
		
		updateCode.run();
				
	} finally {
		inChange= false;
		
		
		if (restoreSelection)
			setSelectionToWidget(oldSelection, false);
		
		
		ISelection newSelection= getSelection();
		if (! newSelection.equals(oldSelection))
			handleInvalidSelection(oldSelection, newSelection);
	}