I'm not sure what you mean there.
I was talking that, usually, in Java with a single JRE you can size them all (the apps, not the Pokemon
). I heard some comments about a nasty compatibility issue (that point updates, which are mostly security-related, caused) with a piece of software (not sure which), but the guy only said that it was causing problems. It was on the Ars OpenForum, where, as you may know, everyone is either a wizard coder or a mega-sized troll.
Of course, it could be possible, but with different versions of Java, as the APIs and the objects structure usually change with major updates. But at least Sun does extensive testing to ensure everything is right (so far, in my own experience, everything went right). Microsoft, in the other hand, simply develop .NET versions. Do you think that kind of fast development, constantly adding features and unneeded extras, would be possible if they had to ensure the maximum compatibility possible? No way, and the way they're going, we might end doing what Carol fears, only to ensure two or three apps could work in our machines (so far, I only have ATI's Catalyst Control Center and in the future, possibly Paint.NET). And considering that to ensure we have true Vista native applications we have to use .NET... well... I feel like o_O.
And what's that he can't upgrade? And those compression problems?