This is reproducible only with marina b11. Not reproducible with marina b10. Changing the arc type at runtime do not have any effect. The new arc type gets updated when there's a repaint because of any other attribute change.

To reproduce, run the below test. Click on the arc to change the arc type

import javafx.stage.*;
import javafx.scene.*;
import javafx.scene.paint.*;
import javafx.scene.input.*;
import javafx.scene.shape.*;

var typeC: Integer = 0;
var arcType: ArcType = ArcType.CHORD;
var arc = Arc {
    centerX: 100
    centerY: 100
    radiusX: 50
    radiusY: 30
    length: 275
    type: bind arcType
    fill: Color.BLUE
    stroke: Color.BLACK
    strokeWidth: 3
    focusTraversable: true
    onMouseClicked: function(e:MouseEvent) {
        if (typeC == 0) {
            arcType = ArcType.OPEN;
            typeC++;
        } else if (typeC == 1) {
            arcType = ArcType.ROUND;
            typeC++;
        } else if (typeC == 2) {
            arcType = ArcType.CHORD;
            typeC = 0;
        }
    }
};
Stage {
    width: 240
    height: 320
    scene: Scene {
        content: arc
    }
};
arc.requestFocus();