Just as a way to look at it (and no, I am not saying to repost it)...
A bug is something that happens that shouldn't happen. It's something that the program wasn't designed to have happen.
Soemthing that happens that you don't like, but works the way it was designed to work, is not a bug.
If I don't like how TABs work in dialogs, doesn't mean that they are a bug.