Button names usually appear in 12-point Chicago. If a button is not available, it appears dimmed. On color systems, dimmed items appear in true gray. Chicago is designed specifically to display well on the screen in all states, including dithered and gray. Other fonts, such as Geneva, which is sometimes used for button names, are rendered illegible when they are dithered.
Buttons usually cause instant actions, described by the name of the button.
Occasionally they require more information before acting. If a button displays another dialog box, use the ellipsis character in the button name to indicate this to the user. The most appropriate situation for a second dialog box to appear would be when a modeless dialog box needed additional information on a limited basis to complete an action. A user typically reads the text in a dialog box until it becomes familiar and then relies on visual cues, such as button names or positions, to respond. Names such as Save, Quit, and Erase Disk allow users to identify and click the correct button quickly.