Run the attached program. It shows a Group containing a Rectangle. Rectangle has blocksMouse set to true. When mouse is clicked on Rectangle, a Node below the Rectangle also receives the event.
This is reproducible only on emulator. On desktop, event will not reach the node below.
To reproduce, run the following code on emulator. Click on the area of the red rectangle overlapping with the blue rectangle underneath. It could be seen that blue rectangle comes on top.

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

public class BlocksMouseTest {
    var redRect: Rectangle = Rectangle {
        x: 70
        y: 70
        width: 60
        height: 80
        blocksMouse: true
        fill: Color.RED
        opacity: 0.8
        onMouseClicked: function(e: MouseEvent) {
            redRect.toFront();
        }
    };
    var blueRect: Rectangle = Rectangle {
        x: 80
        y: 100
        blocksMouse: true
        width: 80
        height: 80
        fill: Color.BLUE
        onMouseClicked: function(e: MouseEvent) {
            blueRect.toFront();
        }
    };
    var group: Group = Group {
        content: [redRect]
    };
    var topGroup: Group = Group {
        content: [blueRect, group]
    };
    init {
        var s = Stage {
            width: 300
            height: 300
            scene: Scene {
                content: topGroup
            }
        };
    }
}
function run() {
    new BlocksMouseTest;
}