Developing User Interfaces for Microsoft Windows

When is a dialog box necessary? Of course, that depends on the dialog box and how it is used. Dialog boxes are often necessary for the following situations:

• Making a feature visible A well-designed dialog box with instructive labels and with controls organized to clearly show their relationships is a very visible mechanism for performing commands. Dialog boxes are also an excellent teaching tool, especially for beginning users. A good dialog box conveys what the command is, what the options are, and what input is needed to perform the command. However, once the command has been mastered, such a dialog box can become the user interface equivalent of training wheels—cumbersome and restrictive—when there are more efficient alternatives.
• Making a feature invisible You can hide advanced features that you don't want beginning users to see by placing them in a separate dialog box. The typical user won't bother clicking a command button labeled Advanced… until he feels comfortable with the program.
• Gathering information required to perform a task Dialog boxes are effective for gathering input, especially complex input. Although there are other interfaces for making simple selections, dialog boxes are often the best way to get text and numeric data to perform a task.
• Showing and changing properties Dialog boxes (actually property sheets) are the standard way to show and change properties in Windows.
• Selecting infrequently used settings and commands Dialog boxes are a good choice for infrequently used settings and commands, allowing you to separate them from the frequently used settings and commands.
• Performing a task unrelated to the task at hand Dialog boxes are a good mechanism for performing an unrelated task. Combining unrelated tasks into a single window is confusing.
• Performing a hazardous task The fact that a modal dialog box has a Cancel button is significant because it gives the user the ability to bail out. A modal dialog box should always be used for a potentially hazardous task like formatting a hard disk.

These are all good reasons to use dialog boxes, but the best programs strive to make sure that you don't need dialog boxes for routine commands. Consider Microsoft Word. It has dozens of dialog boxes, yet for normal word processing you don't need to use any of them except for the Open and Save As dialog boxes. For example, Word has a Font dialog box that allows you to select a font's typeface; its size; whether it is regular, bold, italic, or underlined; its color; and its various other attributes, such as superscript, subscript, small caps, or hidden. However, since the most useful of these attributes are also on the toolbar, I almost never use this dialog box. Surprisingly, the same can be said for most of the other dialog boxes found in Word. If the user constantly has to access a dialog box to perform a routine command, this is a sign of an unnecessary dialog box.

TIP