To add a bit: Microsoft added stuff to the standard packages (java and com.sun, if memory serves), but the stuff they added would have been Windows-only. So you write it on Windows, using what looks like standard packages, and then - surprise! - it won't run everywhere, it will only run on Windows. A nasty, hidden form of lockin. And Microsoft was doing this deliberately, trying for the lockin. That's why Sun sued. And, since the contract prohibited exactly what Microsoft did, Sun won.