MathStretch
A drawn horizontal decoration centered on the math axis. It is a relation atom when used directly in MathText.
| Property | Default | Meaning |
|---|---|---|
| label | "overbrace" | Shape name; a leading backslash is optional. |
| width / height | Shape minimum / natural height | Ordinary Gum allocation lengths. |
| thickness | em(0.04), braces em(0.1), brackets em(0.12) | Thickness in the active math em. |
| head-curve | 0.7 | Arrow and harpoon barb curvature from 0 to 1; see ArrowHead. |
Names include widehat, widecheck, widetilde, utilde, vec,
overbrace/underbrace, overbracket/underbracket, overgroup/undergroup,
overlinesegment/underlinesegment, over/under left/right/bidirectional arrows,
Overrightarrow, and overleftharpoon/overrightharpoon.
The extensible-arrow names are xrightarrow, xleftarrow, xleftrightarrow,
xRightarrow, xLeftarrow, xLeftrightarrow, xlongequal,
xtwoheadrightarrow, xtwoheadleftarrow, xhookrightarrow, xhookleftarrow,
xmapsto, xrightharpoonup, xrightharpoondown, xleftharpoonup,
xleftharpoondown, xrightleftharpoons, xleftrightharpoons,
xrightleftarrows, xtofrom, xrightequilibrium, and xleftequilibrium.
Shapes retain their minimum form under a smaller allocation and report overflow. Color and opacity inherit normally. Wide accents grow modestly in height with width. Use Accent, HorizBrace, or XArrow to position bodies and labels automatically.
Arrow families use core Arrow and ArrowHead with open barbs, including single-barbed harpoons. Constant-width decorations use core lines, polylines, and arcs; tapered braces retain their variable-width outlines.