Ability to drag free-hand shape's start point and end point

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The default control points (blue dots) can only stretch a freehand shape horizontally or vertically.
What I want is to let the first point and the last point acting as archor and stretcher, i.e. when I drag the last point, I can stetch and rotate the shape with the first point fixed, and when I drag the first point, I can stetch and rotate the shape with the last point fixed. All other points should be updated according to the scale and relative rotation angle.

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With Alt pressed, the first point and the last point of a freehand shape show as orange dots, and can be then selected and drag freely.

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Start by tracing the JavaScript client’s freehand-shape control-point handling and how Alt modifies point selection. The feature is done when the first and last points can appear as orange dots and be dragged independently, with the remaining points scaling and rotating around the opposite fixed endpoint.