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
*/
protected void handleOpen(SelectionEvent event) {
	Control control = getControl();
	if (control != null && !control.isDisposed()) {
		ISelection selection = getSelection();
		fireOpen(new OpenEvent(this, selection));
	}
}
/**
 * Handles an invalid selection.
 * <p>
 * This framework method is called if a model change picked up by a viewer
 * results in an invalid selection. For instance if an element contained
 * in the selection has been removed from the viewer, the viewer is free
 * to either remove the element from the selection or to pick another element
 * as its new selection.
 * The default implementation of this method calls <code>updateSelection</code>.
 * Subclasses may override it to implement a different strategy for picking
 * a new selection when the old selection becomes invalid.
 * </p>
 *
 * @param invalidSelection the selection before the viewer was updated
 * @param newSelection the selection after the update, or <code>null</code> if none
 */
protected void handleInvalidSelection(ISelection invalidSelection, ISelection newSelection) {
	updateSelection(newSelection);
}
/**
 * The <code>StructuredViewer</code> implementation of this <code>ContentViewer</code> method calls <code>update</code>
 * if the event specifies that the label of a given element has changed, otherwise it calls super.