A spin box is a text box that accepts a range of values. It incorporates two arrow buttons that allow the user to increase or decrease the current value by a fixed amount.
Guidelines
Use spin boxes for numerical input only. Use a list or option menu when you need the user to select from fixed data sets of other types.
Use a spin box if the numerical value is meaningful or useful for the user to know, and the valid input range is unlimited or fixed at one end only. For example, a control for specifying the number of iterations of some action, or a timeout value. If the range is fixed at both ends, or the numerical values are arbitrary (for example, a volume control), use a slider control instead.
Label the spin box 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 spin box.
Right-justify the contents of spin boxes, unless the convention in the user's locale demands otherwise. This is useful in windows where the user might want to compare two numerical values in the same column of controls. In this case, ensure the right edges of the relevant controls are also aligned.
In an instant-apply property or preference window, validate and apply the contents of a spin box when a spin button is clicked, when it loses focus or when the window is closed, but not after each keypress. Exception: if the field accepts only a fixed number of characters, such as a hexadecimal color code, validate and apply the change as soon as that number of characters have been entered.