Combination Text-List Control (Control Type)

Provide a combination text-list control when the user can either choose a predefined item from the items in the list box for placement into a text field or enter values into a text-entry field that are not in the list box.

Provide a combination text-list control when the user might want to type values into the text-entry field and the list of items in the list box can provide contextual support or otherwise assist the user in completing the text-entry field.

Provide a combination text-list control when the user wants to easily see the last value chosen from a list.

Order the items in the list box in some application-defined way that is meaningful to the user, such as alphabetically, numerically, chronologically, or other such order.

Initially display one of the text items of the list box in the text field if a meaningful, application-specific one can be selected. Otherwise display nothing.

Use either a single or a browse selection model in the list box.

Use the browse selection model in the list box if a text-entry field is used and the list box cannot take focus.

Use the browse selection model in the list box if prefix completion is in use.

Move input focus to the text field if the user presses the SELECT button on an item in the list box and the list box cannot take focus. The item indicated is selected as usual, however.

If the user presses ↓ when focus is in the text field and the list box is not displayed, do one of the following:

If the user presses keys used for vertical navigation or paging when focus is in the text field and the list is not displayed, do one of the following:

If the user presses a key used for vertical navigation or paging when focus is in the text field and the list box is displayed, navigate in the list as indicated, select the cursored list item, and display it in the text field.

A combination text-list control whose list box cannot take focus is a tab group.

When focus is in a text-list control whose list box is temporarily displayed and keyboard navigation (for example, tab group or window navigation) is used to move the focus elsewhere, the list box is removed if currently displayed.

Display the list box when the user presses Alt ↓ if the text field has focus and the list box is not currently displayed.

When a text-entry field in a combination text-list control has focus, input of printing characters enters them into the text field, with or without prefix navigation.

When a text-display field in a combination text-list control has focus, use entered printing characters either for prefix completion or for first-letter cursor navigation in the associated list.

When a list item is selected, other than by prefix navigation, place the text of the newly selected list item in the text field.

When a newly selected list item is placed in the text field and is selected in the text field, place the cursor at the end of the text field.

When a newly selected list item is placed in the text field, other than by prefix completion, select it in the text field as a persistent selection.

When scrolling the text field horizontally, scroll the associated list horizontally in conjunction with it.

Provide vertical scroll bars if some of the items in the list box are not displayed when the list box is displayed.

Make the text field at least as wide as the list box would be if it were displayed.

If the window in which the combination text-list control is displayed is sized so that even two items cannot be displayed in the list box, do not display the list box permanently.

If the items in the list box are wider than the list box, support horizontal scrolling in the list box.

If the list box is not always displayed, include a list cascade element from which the list box can be displayed.

If enough space is not available to display the text field and the list cascade button, clip the text field before clipping the list cascade button horizontally.

Use a down arrow graphic placed to the right of the text field, and visually distinct from it, as the list cascade button. For bidirectional and vertical language guidelines, see Chapter 11.

Make the text field the same width as the list box if the list box is permanently displayed.

When a user increases the size of the window in which the combination text-list control is displayed, increase the number of items displayed in the list box.

When a user decreases the size of the window in which the combination text-list control is displayed, decrease the number of items displayed in the list box.

Make the list box large enough to display at least two items.