Bug 38140 SnippetOpenOnSelectionAction subclasses OpenAction although OpenAction isn't made for subclassing
org.eclipse.jdt.ui/ui/org/eclipse/jdt/ui/actions/SelectionDispatchAction.java
* 
	 * @param selection the selection this action is working on
	 */
	public void update(ISelection selection) {
		dispatchSelectionChanged(selection);
	}
	/**
	 * Notifies this action that the given structured selection has changed. This default
	 * implementation calls <code>selectionChanged(ISelection selection)</code>.
	 * 
	 * @param selection the new selection
 	 */
	public void selectionChanged(IStructuredSelection selection) {
		selectionChanged((ISelection)selection);
	}
	/**
	 * Executes this actions with the given structured selection. This default implementation
	 * calls <code>run(ISelection selection)</code>.
	 */
	public void run(IStructuredSelection selection) {
		run((ISelection)selection);
	}
	
	/**
	 * Notifies this action that the given text selection has changed.  This default
	 * implementation calls <code>selectionChanged(ISelection selection)</code>.
	 * 
	 * @param selection the new selection
 	 */
	public void selectionChanged(ITextSelection selection) {