Bug 327585 Commands, Handlers, and keybindings should use leaf lookup
bundles/org.eclipse.e4.ui.services/src/org/eclipse/e4/ui/internal/services/ContextContextService.java
* String)
	 */
	public void activateContext(String id) {
		Set<String> locals = (Set<String>) eclipseContext
				.getLocal(LOCAL_CONTEXTS);
		if (locals == null) {
			locals = new HashSet<String>();
		} else {
			
			locals = new HashSet(locals);
		}
		locals.add(id);
		eclipseContext.set(LOCAL_CONTEXTS, locals);
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.eclipse.e4.ui.services.EContextService#deactivateContext(java.lang
	 * .String)
	 */
	public void deactivateContext(String id) {
		Set<String> locals = (Set<String>) eclipseContext
				.getLocal(LOCAL_CONTEXTS);
		if (locals != null) {
			
			locals = new HashSet(locals);
			locals.remove(id);
			eclipseContext.set(LOCAL_CONTEXTS, locals);
		}