Add missing reflection config in the vertical splitter.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@tp/tp-splitter",
-  "version": "2.1.0",
+  "version": "2.1.1",
   "description": "",
   "main": "tp-splitter.js",
   "scripts": {

tp-vsplitter.js

@@ -56,9 +56,9 @@ class TpVSplitter extends LitElement {
 
   static get properties() {
     return {
-      leftHidden: { type: Boolean },
-      rightHidden: { type: Boolean },
-      dragging: { type: Boolean },
+      leftHidden: { type: Boolean, reflect: true },
+      rightHidden: { type: Boolean, reflect: true },
+      dragging: { type: Boolean, reflect: true },
       minSideWidth: { type: Number },
       lateResize: { type: Boolean }, // if true, the panels will not be reized until the dragging is finished.
       initialLeftWidth: { type: String },