Simple serialization entities fixes and tests

js/input/mouse/IMouseClickDrag.js

@@ -140,6 +140,9 @@ export default class IMouseClickDrag extends IPointing {
     #trackingMouse = false
     #movementListenedElement
     #draggableElement
+    get draggableElement() {
+        return this.#draggableElement
+    }
 
     clickedOffset = /** @type {Coordinates} */([0, 0])
     clickedPosition = /** @type {Coordinates} */([0, 0])

js/input/mouse/MouseMoveNodes.js

@@ -1,8 +1,20 @@
 import MouseMoveDraggable from "./MouseMoveDraggable.js"
 
+/** @typedef {import("./IMouseClickDrag.js").Options} Options */
+
 /** @extends {MouseMoveDraggable<NodeElement>} */
 export default class MouseMoveNodes extends MouseMoveDraggable {
 
+    /**
+     * @param {NodeElement} target
+     * @param {Blueprint} blueprint
+     * @param {Options} options
+     */
+    constructor(target, blueprint, options = {}) {
+        super(target, blueprint, options)
+        this.draggableElement.classList.add("ueb-draggable")
+    }
+
     startDrag() {
         if (!this.target.selected) {
             this.blueprint.unselectAll()