The control that combines the functionality of a textbox and a listbox is known as a combo box.
Understanding the Combo Box
A combo box is a fundamental element in graphical user interfaces (GUIs). As defined in the reference, it is a commonly used widget that merges two distinct controls:
- A single-line editable textbox: This allows the user to type a value directly into the control.
- A drop-down list or list box: This provides a predefined list of options from which the user can select a value.
Essentially, a combo box offers users flexibility. They can either quickly type a known value into the textbox portion or browse and select from the list of available options. This duality makes it highly versatile for various input scenarios.
How it Works
Typically, the list portion of a combo box remains hidden until the user clicks a small arrow or button next to the textbox. This action "drops down" the list, making the available options visible. Once an item is selected from the list, it appears in the textbox area. If the user types into the textbox, the value they enter becomes the control's value, regardless of whether it's in the list or not (depending on the specific implementation).
Key Characteristics
- Combination: Merges text entry (textbox) with selection from a list (listbox/drop-down).
- Flexibility: Supports both typing and selecting input methods.
- Space-Saving: The list is usually hidden until needed, saving screen real estate compared to a persistent listbox.
- Common Use Cases: Ideal for forms where users might enter a value not in the standard list but where providing suggestions is helpful (e.g., selecting a country from a long list, choosing a predefined size, entering a custom value).
By integrating the typing capability of a textbox with the selection power of a listbox, the combo box provides an efficient and user-friendly way to handle input, especially when dealing with a potentially large or dynamic set of options.
