Some objects in dialog boxes and toolboxes are available only
under certain circumstances. When an object is unavailable, it appears dimmed
in the dialog box.
Items are usually dimmed as a result of some other setting in the dialog
box. For example, if Use settings below is not selected,
the image size options below it are not available and appear dimmed, as shown
below.
Context-sensitive help is available even for dimmed options, although
tooltips are not.