Drop-down lists are used to select from a mutually exclusive set of options. They can be useful when there is insufficient space in a window to use a group of radio buttons or a single-selection list, with which they are functionally equivalent.
Figure 6.17. A drop-down list showing current selection (left) and the list of available choices when clicked on (right)
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Recommendations:
Do not use drop-down lists with fewer than three items, or more than about ten. To offer a choice of two options, use radio buttons or toggle buttons. To offer a choice of more than ten options, use a list.
Do not initiate an action when the user selects an item from an drop-down list. However, if used in an instant-apply property or preference window, update the setting that the menu represents immediately.
Selecting an item from a drop-down list should not affect the values of any other controls. It may sensitize, insensitize, hide or show other controls, however.
Label the drop-down list with a text label above it or to its left, using sentence capitalization. Provide an access key in the label that allows the user to give focus directly to the drop-down list.
Use sentence capitalization for drop-down list items, for example Switched movement
- Do not assign shortcut keys to option menu items by default. The user may assign their own shortcut keys in the usual way if they wish, however.
Assign an access key to every drop-down list item. Ensure each access key is unique within the enclosing window or dialog, not just within the menu.
Do not assign shortcut keys to drop-down list items by default. The user may assign their own shortcut keys in the usual way if they wish, however.
Do not use a drop-down list in a situation where it may have to show a property of a multiple selection, as drop-down lists have no concept of mixed state. Use a group of radio or toggle buttons instead, as these can show set, unset or mixed states.
Do not use submenus on a drop-down list.
You should normally use radio buttons or a list instead of drop-down lists, as those controls present all the available options at once without any further interaction. However, drop-down lists may be preferable in a window where:
there is little available space
the list of options may change over time
the contents of the hidden part of the menu are obvious from its label and the one selected item. For example, if you have an option menu labelled "Month:" with the item "January" selected, the user might reasonably infer that the menu contains the 12 months of the year without having to look.
Option menus can also be useful on toolbars, to replace a group of several mutually-exclusive toggle buttons.
Drop-down lists can also be useful on toolbars, to replace a group of several mutually-exclusive toggle buttons.