For text, this is `relative'(?) to the current alignment.
For barline, space after a thick line.")
+(grob-property-description 'layer number? "The output layer [0..2]. The default is 1.")
(grob-property-description 'left-padding number? "space left of accs.")
(grob-property-description 'length number? "Stem length for unbeamed stems, only for user override.")
(grob-property-description 'lengths list? "Stem length given multiplicity of flag.")