@Override
	public void addChild(IVisualPart<? extends Node> child, int index) {
		if (children.contains(child)) {
			throw new IllegalArgumentException("Cannot add " + child
					+ " as child of " + this + " because its already a child.");
		}

		// System.out.println(
		// "Add child " + child + " to " + this + " with index " + index);

		children.add(index, child);
		child.setParent(this);

		refreshVisual();
		doAddChildVisual(child, index);
		child.refreshVisual();

		if (isActive()) {
			child.activate();
		}
	}