1. I create style Y, based on style X.
2. I change font for style X - font of style Y is changed too.
3. I change font for style Y only.
4. I change font for style X - font of style Y isn't changed.

How to reset changes (in any time, not by using Undo option just after),
made in step 3? In other words, how to say to the style: "reset your
attributes to those known from your base-style"?

Thanks in advance

x-plorer