protected void applyActiveChanges() {
		boolean changed = false;
		for (int i = 0; i < changes.size(); i++) {
			if (changes.get(i).isActivation()) {
				changes.get(i).apply(courseModel);
				changes.remove(i);
				changeSelected.remove(i);
				i--;
				changed = true;
			}
		}
		if (changed)
			finishModification();
	}