I think another example was by joelonsoftware, where when MS moved to win 95, they actually ran popular software looking for bugs, and found the SimCity would use-after-free (which, before 95 wouldn't crash), so they modified their OS to leave that memory cell intact even after free.
They do it to this day. Application compatibility assistant or whatever its called now runs on every single machine and hot patches loaded programs. Malware authors love it.
