This is a ButtonFacade skin called ButtonFacade_Shadow. In credit to StormFX and his ButtonFacade Code. This skin is inspired from Freebaser's shadowed borders.
This ButtonFacade skin requires ButtonFacade in order to work.
If you use this skin, please credit Ferous as well as StormFX, as the texture is made entirely from scratch by me and the code is made from StormFX's. Thanks!