With a Combo box combo box, users make a choice among a list of mutually exclusive values. Users can choose one and only one option. Choosing a value from a the provided list can be done by typing the name of the value or by selecting the element from the list.

A combo box is similar to a Drop-down list with the difference that the drop down list does not support typing. For keyboard shortcuts see the documentation of the drop-down list.

Combo boxes that support null will show a Command button on top of the list (see figure 2) that can be use to set the value to null. Alternatively you can use the backspace key.

Figure 1: Typing in a combo box with autocomplete

Figure 2: A combo box with opened list.