rich-text-block
One line of text on a UI stage built from styled pieces: each entry of its `runs` has its own text, size, weight, colour and italic; it does not wrap.
rich-text-block(align=left w=1 h=1)
Attributes
aligntext`left` (default), `center` or `right` within `w`.12×wnumberBox width in stage units; without it, the runs' own width.12×hnumber2×xnumber2×ynumber2×