programming-for-dummies

Designing a User Interface 305
A well-designed user interface should always show all possible choices and
not overwhelm the users with choices they can’t pick anyway.
Tolerate mistakes
User interfaces are meant for people to use, and it’s no surprise that people
make mistakes. Sometimes they type in the wrong data and sometimes they
give a command that they didn’t really want to give.
If you make a mistake, you should be able to
✦ Undo or take back that mistake.
✦ Give the right command or data.
Book II
Chapter 10
Unfortunately, too many user interfaces don’t let users undo their mistakes,
which can make the user anxious and timid because he’s afraid that if he
does something wrong, he can’t ever reverse his mistake. As a result, anxious
and timid users tend not to trust a program or use it to its maximum
capabilities.
Even worse is when user interfaces provide cryptic feedback if the user does
something wrong. Examining the error message in Figure 10-19, can you tell
what you might have done wrong and what you can do in the future to make
sure this error message doesn’t appear again?
Principles of User
Interface Design
Figure 10-19:
A cryptic
error
message is
meaningless
and
frustrating
because the
user never
knows how
to avoid this
problem in
the future.
Cryptic messages can make users feel as if the program is scolding them. As
a result, users are less likely to enjoy using the program and probably won’t
take full advantage of all its features either, if they even bother using the program
at all.