Drag out from a segment, corner, circle or arc to place a dimension; plain clicks pick two points or two lines. Radial dimensions on perfect arcs, picas, Away/Between and Left/Center/Right text placement. The Properties panel edits a selected dimension, with Apply to All (dimension.applyToAll) and Set as Default. Dimension Selected Paths, the Arc/R/Ø prefixes and the custom defaults are left out. The refresh returns at once in documents without dimensions (Document::dimensions); a linked dimension moved on its own keeps its place; modes, units, line types, arrows and text placement are enums; the tool has its own icon.
Osama Amin