Window Components Window Operations Secondary Windows Controls     Buttons     Check Boxes     List Boxes     Text Fields     Text Boxes     Combo Boxes     Other Controls... Menus Toolbars & Status Bars Property Sheets Dialog Boxes Message Boxes Palette Windows Popup Windows

Combo Boxes: A combo box is a control that combines a text box with a list box, as shown in Figure 7.19. This allows the user to type in an entry or choose one from the list. The text box and its associated list box have a dependent relationship. As text is typed into the text box, the list scrolls to the nearest match. In addition, when the user selects an item in the list box, it automatically uses that entry to replace the content of the text box and selects the text. The interface for the control follows the conventions supported for each component, except that the UP ARROW and DOWN ARROW keys move only in the list box. LEFT ARROW and RIGHT ARROW keys operate solely in the text box. Drop-down Combo Boxes: A drop-down combo box, as shown in Figure 7.20, combines the characteristics of a text box with a drop-down list box. A drop-down combo box is more compact than a regular combo box; it can be used to conserve space, but requires additional user interaction required to display the list. The closed state of a drop-down combo box is similar to that of a drop-down list, except that the text box is interactive. When the user clicks the control's menu button the list is opened. Clicking the menu button a second time, choosing an item in the list, or clicking another control closes the list. Provide a static text field label for the control and assign an access key. Use the access key so the user can navigate to the control. You can also support the TAB key or arrow keys for navigation to the control. When the control has the input focus, when the user presses the UP ARROW or DOWN ARROW or ALT+UP ARROW or ALT+DOWN ARROW key, the list is displayed. When the control has the input focus, pressing a navigation key, such as the TAB key, or an access key or ALT+UP ARROW or ALT+DOWN ARROW to navigate to another control closes the list. When the list is closed, preserve any selection made while the list was open, unless the user presses a Cancel command button. The ESC key also closes the list. When the list is displayed, the interdependent relationship between the text box and list is the same as it is for standard combo boxes when the user types text into the text box. When the user chooses an item in the list, the interaction is the same as for drop-down lists - the selected item becomes the entry in the text box.