Reorder States - and its purpose is what exactly?

Prior to re-ordering states, states were ordered in sequence of their creation. With the feature enhancement it allows you to move it in sequence. We added the state renaming as well. 

Thus you have more control over how the states display when working with the states. A lot of people like to re-organize the states if they create additional states after the fact and then want to move them into the sequence that looks better while they're working in the states panel.

How you organize the states in the panel has no implication on how the states behave since they're either triggered because of the pre-built settings like the visited state or they're triggered with a trigger.

Your states shouldn't move around when you open and close them. I did some tests to see if something's not working right and am not experiencing that. If that continues for you, contact our support team so they can look into what's happening.