ComboBoxes display a textual value and a button to the right to edit that value.
In appearance, ComboBoxes look like ButtonEdits. The difference is that when you click on a ComboBox's button, a drop-down list of possible values is displayed.
There are many usefuls tricks in the use of ComboBoxes :
•If a ComboBox is focused, and the drop-down list is visible, you can move the selection up and down using the UP and Down keys. Using the HOME key brings you to the top of the list, and using the END key brings you to the end of the list.
•To "click" on a selected item using the keyboard, press the ENTER or RETURN key.
•If a ComboBox is focused, you can cycle up or down the list of values, without opening the drop-down list, using the CTRL-UP and CTRL-DOWN key combinations.
•When the drop-down list is displayed, you can move to a desired entry by typing the first letter of that entry. In the example above, typing E would move the selection to "Easter". If there are more than one entry beginning with the same letter (for example a list of the 12 months), typing a letter a second time brings you to the second occurence of an entry starting with that letter, and so on.
•You can close the drop-down list and cancel any change in selection by using the ESC key.
Note that in a few cases, the text in the ComboBox can be edited to enter a value not found in the drop-down list (example below comes from from the Help Wizard).