Bug 263544 [context] Add dependency injection context -> user object
examples/org.eclipse.e4.demo.e4photo/src/org/eclipse/e4/demo/e4photo/Thumbnails.java
private Gallery gallery;
	private GalleryItem group;
	private final ISelectionService selectionService;
	private final IBackgroundRunner backgroundRunner;
	public Thumbnails(Composite parent, ISelectionService selectionService, IBackgroundRunner backgroundRunner) {
		this.selectionService = selectionService;
		this.backgroundRunner = backgroundRunner;