The “Shape options” dialog has a small lock icon to lock the relative width and height settings. The lock icon is always that of a closed lock. When you click on it to turn it on it turns from black to blue. The color shift is subtle and hard to distinguish, especially on a smaller screen like a Surface Pro.
Most applications I’ve seen that have some kind of Lock icon show the lock open when it’s not set, and closed when it is set. This would make it much easier to see whether or not the lock is set.
