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
* in the viewer widget changes.
 * </p>
 * <p>
 * The default implementation of this method notifies all 
 * selection change listeners recorded in an internal state variable.
 * Overriding this method is generally not required; 
 * however, if overriding in a subclass, 
 * <code>super.updateSelection</code> must be invoked.
 * </p>
 * @param selection the selection, or <code>null</code> if none
 */
protected void updateSelection(ISelection selection) {
	SelectionChangedEvent event = new SelectionChangedEvent(this, selection);
	fireSelectionChanged(event);
}
/**
 * Returns whether this structured viewer is configured to use an internal
 * map to speed up the mapping between elements and SWT items.
 * <p>
 * The default implementation of this framework method checks whether the
 * internal map has been initialized.
 * </p>
 *
 * @return <code>true</code> if the element map is enabled, and <code>false</code> if disabled
 */
protected boolean usingElementMap() {
	return elementMap != null;
}    
}