When you design user interfaces, it's a good idea to keep two principles in mind:
These are not, strictly speaking, facts, but you should act as if they are facts, for it will make your program easier and friendlier.
Users don't read the manual.
First of all, they may not actually have the manual. There may not be a manual. If there is one, the user might not have it for all kinds of logical reasons: they're on a plane; they're using a downloaded demo version from your Web site; they're at the beach and the manual is at work; their IS department never gave them the manual. ...