It would be the first program that let you do that, as long as I know.
Contacts (material boundaries) are often weaker that the soils in contact.
Most programs don't let you assign a strength criteria to that surface, they just use the properties of the soil above the contact when you are calculating the FOS of a user generated surface or a mixed surface.
So when you have a fault or a weak contact you have to generate a thin layer of material to be able to take it into account.
It would be great to be able to assign strenth properties to material boundaries and have an option to generate mixed surfaces in an automatic way similar to the way Slide programs does when you activate it (but only with the external boundary and in a limited way).
If a circle crosses under a material contact with weak porperties assigned, the program could automatically project the slice base of eache slice under that contact in the vertical direction (to the nearest material boundary above it) and assign the strenght of the contact to that slice bases.
That would be a great way of calculating mixed failures over contacts, faults, and weak layers, generating mixed surfaces in a convenient and easy way.