A list box is used to display many options from which one or more can be selected. A small number of options is displayed in the list box window, and a scroll bar is used to view additional options. A single select list box can save precious screen real estate when there are many options. They can also be used as an alternative to dropdowns. Using the list box MULTIPLE attribute, users can select more than one option (see Figure 15).
Include a brief instruction at the top of list boxes to indicate whether users can select one or more options. For novice Web users, you should explain how to select more than one option (on the PC, the keyboard combination is CTRL+click; on the Macintosh it is APPLE+click).
Variable length options
As with all Web widget options, list box options should be similar in length to facilitate scanning. The goal should be to make options as short as possible while still being clear.
No logical order
List boxes are similar to dropdowns in that the order of options should be logical to users. Again, the best way to find out what's logical to users is to ask them. Like dropdowns, users can also use keyboard shortcuts to jump down the list of options.
On the Monster job search multiselect list box (see Figure15), there is no default option. To save users a click, it is wise to default to the most likely choice. If the site is personalized for the user, the default could be the user's home state or the last state for which a search was conducted. If the site is not personalized, a logical default might be "Select All."