"Make into Control" option in Microsoft Blend 2015

I have tried to use this Tool and I don't understand its purpose. In previous versions, it created a UserControl out of the selected controls. Now it creates a ButtonStyle for what I have seen.

How can I use this tool?

This is still a little busted in Blend 2022 but here's how you get it working (for posterity).

What happens now is you choose "Make Into UserControl" and then it pops up with a box that asks you to name it. Then, nothing happens.

Here's the fix:

1. Create a new empty user control and name it however you want it to be named.
2. Go back to the control you want to make into a control, choose "Make Into UserControl" again. Put the name of the control in there that you just created.

For whatever reason, it silently fails if the user control doesn't exist, but it will write into one that does.