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The Principles of Good Form Design
When you design a form, you should maintain as much consistency as possible. Keep the
following design concepts and tips in mind:
- Consistency of forms. Make all the forms in a multiform application consistent
with each other. A good form should display the same information in the same way, all the
time. Therefore, don't call a data item Vendor No. on one form or control and then call
the item Vendor Num elsewhere. This makes the form and application more difficult to
understand. If the same information is displayed differently on different forms, it should
be for a good reason-not because it looks better. Also, don't change labels on the same
command buttons. If one form's command button caption is
Cancel, don't
change the caption to Quit on another form's command button.
- Consistency of standards. Use the same standards throughout the application. Name
controls, procedures, variables, and other objects consistently. Prefix variables to help
identify their data types, or use data-type suffix characters.
- Consistency of button location. When possible, locate similar command buttons in
the same positions on all forms. Don't, for example, place an E
xit
command button in the center of one form and in the lower-right corner of another form.
- Consistency of color. Use color to make important information stand out. Set
foreground and background colors so that they blend well; don't use clashing colors or try
to impress. For the best results, stick to the standard Windows colors used in major
applications such as Microsoft Word. (You could add a surprise color for warning purposes,
such as a negative balance in a checkbook program.)
- Consistency of readability. Make the form easy to read. Don't use all uppercase
letters for titles or other labels except in rare cases. Keep lots of white space
(the blank areas on a form) on the form for clarity. Use a different font for labels and
for text boxes that the labels describe, unless the controls' border style and background
properties help distinguish them already. Don't mix too many fonts on the same form,
however.
- Consistency of clarity. Don't clutter the form with too much information. Express
but don't try to impress. Although the VBScheduler application form shown in Figure 33.1
is simple, the form is perfect for the application and gives users all available
information without too much clutter. VBScheduler requires only a single form, but if the
form gets too crowded, using a second form is smarter than squeezing too many more
controls on one.
- Consistency of simplicity. Make data entry simple. Use a drop-down list box when
users need to select from a limited number of choices. Analyze the focus order so that
pressing the Tab key sends the focus to the next control in line to receive the focus. Add
hot keys to text-box labels so that users can move directly to the text box. Never let
users answer Yes or No questions by typing Yes
or No, but supply check boxes, option
buttons, and command buttons for such controls. The simpler you make data entry, the fewer
user errors will occur.
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