Bug 204458 [Commands] Allow menu and toolbars to fire execution events
Keybindings will currently fire execution events when executing actions from the action framework. i.e. IActions with their actionDefinitionId set and IActionDelegates with the definitionId attribute in their action contributions. But it would be nice if selecting the menu or tool item would also fire the equivalent events. PW
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/CommandManager.java
*            The listener to be removed; must not be <code>null</code>.
	 */
	public final void removeCommandManagerListener(
			final ICommandManagerListener listener) {
		removeListenerObject(listener);
	}
	/**
	 * Removes an execution listener from this command manager.
	 * 
	 * @param listener
	 *            The listener to be removed; must not be <code>null</code>.
	 */
	public final void removeExecutionListener(final IExecutionListener listener) {
		if (listener == null) {
			throw new NullPointerException("Cannot remove a null listener"); 
		}
		if (executionListeners == null) {
			return;
		}
		executionListeners.remove(listener);
		if (executionListeners.isEmpty()) {
			executionListeners = null;
			
			final Iterator commandItr = handleObjectsById.values().iterator();
			while (commandItr.hasNext()) {
				final Command command = (Command) commandItr.next();
				command.removeExecutionListener(executionListener);
			}
			executionListener = null;
		}