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
* This method is internal to the framework; subclassers should not call
 * this method.
 * </p>
 *
 * @param the element
 * @return the corresponding widget, or <code>null</code> if none
 */
protected abstract Widget doFindItem(Object element);
/**
 * Copies the attributes of the given element into the given SWT item.
 * The element map is updated according to the value of <code>fullMap</code>.
 * If <code>fullMap</code> is <code>true</code> then the current mapping
 * from element to widgets is removed and the new mapping is added. 
 * If fullmap is <code>false</code> then only the new map gets installed.
 * Installing only the new map is necessary in cases where only
 * the order of elements changes but not the set of elements.
 * <p>
 * This method is internal to the framework; subclassers should not call
 * this method.
 * </p>
 *
 * @param item
 * @param element the element
 * @param fullMap <code>true</code> if mappings are added and removed,
 *   and <code>false</code> if only the new map gets installed
 */
protected abstract void doUpdateItem(
	Widget item,
	Object element,
	boolean fullMap);