About the ComboBox component

A combo box can be static or editable. A static combo box allows a user to make a single selection from a drop-down list. An editable combo box allows a user to enter text directly into a text field at the top of the list, as well as selecting an item from a drop-down list. If the drop-down list hits the bottom of the document, it opens up instead of down. The combo box is composed of three subcomponents: a Button component, a TextInput component, and a List component.

When a selection is made in the list, the label of the selection is copied to the text field at the top of the combo box. It doesn't matter if the selection is made with the mouse or the keyboard.

A ComboBox component receives focus if you click the text box or the button. When a ComboBox component has focus and is editable, all keystrokes go to the text box and are handled according to the rules of the TextInput component (see TextInput component), with the exception of the following keys:

Key	Description
Control+Down	Opens the drop-down list and gives it focus.
Shift +Tab	Moves focus to the previous object.
Tab	Moves focus to the next object.

When a ComboBox component has focus and is static, alphanumeric keystrokes move the selection up and down the drop-down list to the next item with the same first character. You can also use the following keys to control a static combo box:

Key	Description
Control+Down	Opens the drop-down list and gives it focus.
Control+Up	Closes the drop-down list, if open.
Down	Selection moves down one item.
End	Selection moves to the bottom of the list.
Escape	Closes the drop-down list and returns focus to the combo box.
Enter	Closes the drop-down list and returns focus to the combo box.
Home	Selection moves to the top of the list.
Page Down	Selection moves down one page.
Page Up	Selection moves up one page.
Shift +Tab	Moves focus to the previous object.
Tab	Moves focus to the next object.

When the drop-down list of a combo box has focus, alphanumeric keystrokes move the selection up and down the drop-down list to the next item with the same first character. You can also use the following keys to control a drop-down list:

Key	Description
Control+Up	If the drop-down list is open, focus returns to the text box and the drop-down list closes.
Down	Selection moves down one item.
End	The insertion point moves to the end of the text box.
Enter	If the drop-down list is open, focus returns to the text box and the drop-down list closes.
Escape	If the drop-down list is open, focus returns to the text box and the drop-down list closes.
Home	The insertion point moves to the beginning of the text box.
Page Down	Selection moves down one page.
Page Up	Selection moves up one page.
Tab	Moves focus to the next object.
Shift-End	Selects the text from the insertion point to the End position.
Shift-Home	Selects the text from the insertion point to the Home position.
Shift-Tab	Moves focus to the previous object.
Up	Selection moves up one item.

Note: The page size used by the Page Up and Page Down keys is one less than the number of items that fit in the display. For example, paging down through a ten-line drop-down list will show items 0-9, 9-18, 18-27, and so on, with one item overlapping per page.

For more information about controlling focus, see Creating custom focus navigation or FocusManager class.

A live preview of each ComboBox component instance on the Stage reflects changes made to parameters in the Property inspector or Component Inspector panel while authoring. However, the drop-down list does not open in the live preview and the first item displays as the selected item.

When you add the ComboBox component to an application, you can use the Accessibility panel to make it accessible to screen readers. First, you must add the following line of code to enable accessibility:

mx.accessibility.ComboBoxAccImpl.enableAccessibility();

You only enable accessibility for a component once no matter how many instances you have of the component. For more information, see Creating Accessible Content.