Appearance / Buttons: Add Border hover color

Currently it is impossible to create a button that has a different border color on hover than on default.

Example of expected settings:
-> default -> Button color: white, font-color: red, border color: red
-> hover -> button color: white, font-color: blue, border color: blue

It's not possible to define a border color for the hover state.

This is a basic design element that we would like to have implemented.