{ $class-description "A track is like a " { $link pack } " except each child is resized to a fixed multiple of the track's dimension in the direction of " { $snippet "orientation" } ". Tracks are created by calling " { $link <track> } "." } ;
{ $description "Creates a new track which lays out children along the given orientation, either " { $link horizontal } " or " { $link vertical } "." } ;
{ $values { "gadget" gadget } { "track" track } { "constraint""a number between 0 and 1, or " { $link f } } }
{ $description "Adds a new child to a track. If the constraint is " { $link f } ", the child always occupies its preferred size. Otherwise, the constrant is a fraction of the total size which is allocated for the child." } ;