Why defining a style based on (linked to) another style, you cannot easily revert one modified attribute to the inherited (copied) one (once you pressed OK). If you changed an attribute by mistake, you can only reset the complete style (which is not very efficient and satisfying).
Therefore I suggest a dialog that pops up when you "reset" a style that lists all modifies attributes (relative to the linked style) with a checkbox. If checked that attribute is reset to the inherited value; if unchecked, it remains.
That seems to be an easy to understand solution for the problem.