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/CommandEvent.java
/**
	 * The bit used to represent whether the command has changed its category.
	 */
	private static final int CHANGED_CATEGORY = LAST_USED_BIT << 1;
	/**
	 * The bit used to represent whether the command has changed its handler.
	 */
	private static final int CHANGED_HANDLED = LAST_USED_BIT << 2;
	/**
	 * The bit used to represent whether the command has changed its parameters.
	 */
	private static final int CHANGED_PARAMETERS = LAST_USED_BIT << 3;
	
	/**
	 * The bit used to represent whether the command has changed its return type.
	 * 
	 * @since 3.2
	 */
	private static final int CHANGED_RETURN_TYPE = LAST_USED_BIT << 4;