I've done this in documentation in order to show a visual indicator of what the user should be clicking on, or filling in next. This is especially important in

I've done this in documentation in order to show a visual indicator of what the user should be clicking on, or filling in next. This is especially important in programs with confusing or ambiguous UIs (Find the "Settings" option in a Lotus Notes email database? <shiver>). Ideally, it wouldn't be necessary, but it can help as an extra guide in docs.