docs: public void setIndex(int index) {
          ElementBase parent = getParent();
          
          if (parent == null) {
              CWFException.raise("Element has no parent.");
          }
          
          int currentIndex = parent.children.indexOf(this);
          
          if (currentIndex < 0 || currentIndex == index) {
              return;
          }
          
          parent.moveChild(currentIndex, index);
      }