Bug 126414 [Commands] handlers: Provide help context ids
For commands and handlers to replace actions, they need to be capable of providing help context identifiers. For an example, see OpenResourceHandler in org.eclipse.ui.ide. This help context id will need to be definable through XML and through code.
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/Command.java
/**
	 * Removes a listener from this command.
	 * 
	 * @param commandListener
	 *            The listener to be removed; must not be <code>null</code>.
	 * 
	 */
	public final void removeCommandListener(
			final ICommandListener commandListener) {
		if (commandListener == null) {
			throw new NullPointerException(
					"Cannot remove a null command listener"); 
		}
		removeListenerObject(commandListener);
	}
	/**
	 * Removes a listener from this command.
	 * 
	 * @param executionListener
	 *            The listener to be removed; must not be <code>null</code>.
	 * 
	 */
	public final void removeExecutionListener(
			final IExecutionListener executionListener) {
		if (executionListener == null) {
			throw new NullPointerException(
					"Cannot remove a null execution listener"); 
		}
		if (executionListeners != null) {
			executionListeners.remove(executionListener);