Hi,
apparently RTLabelled (or rather TRConstraint) doesn't respect bezier line (not unexpected), and thus probably also all non-straight-line elements (RTMultiLine, RTSomethingGradientLine, maybe others). I am now working on a solution for our heavily modified dynamic multiline, so maybe the solution would be applicable also for the lines in roassal.
Example: ~~~~~~~~~~~~~~~ | v shape edge els | v := RTView new. shape := RTEllipse new size: 10; color: (Color purple alpha: 0.3). els := (shape elementsOn: (1 to: 3)) @ RTDraggable. v addAll: els . RTHorizontalLineLayout on: v elements.
v elements first translateBy: -50 @ 50. v elements last translateBy: 150 @ 100.
edge := (RTBezierLine new controllingElements: v elements) edgeFrom: els first to: els last. v add: edge. edge @ (RTLabelled new text: 'a text').
^ v ~~~~~~~~~~~~~~~~
Peter