Bug/cv2 2000 ghost page has duplicate element (surveyjs#2011)

* fixed surveyjs#2000

* work for the surveyjs#2000

Author: dmitry-kurmanov

packages/survey-creator-core/src/components/page.ts

@@ -27,14 +27,15 @@ export class PageViewModel<
     page["surveyChangedCallback"] = () => {
       this.isPageLive = !!page.survey;
     };
-    if(this.isGhost) {
+    if (this.isGhost) {
       this.updateActionsProperties();
       this.page.registerFunctionOnPropertiesValueChanged(
         ["title", "description"],
         () => {
           this.addGhostPage();
         }
       );
+      this.patchPageForDragDrop(this.page, this.addGhostPage);
     }
     this.page.onFirstRendering();
     this.page.updateCustomWidgets();
@@ -48,6 +49,15 @@ export class PageViewModel<
       this.onPageSelectedCallback();
     }
   }
+  private patchPageForDragDrop(page: PageModel, addGhostPage: () => void) {
+    // need for the drag drop see https://github.com/surveyjs/survey-library/blob/871492817561de11f934ebdf50481770300a396a/src/dragdrop/survey-elements.ts#L266
+    page["_isGhost"] = true;
+    page["_addGhostPageViewModel"] = () => {
+      delete page["_isGhost"];
+      delete page["_addGhostPageViewModel"];
+      addGhostPage();
+    };
+  }
   public dispose() {
     super.dispose();
     this.page.unRegisterFunctionOnPropertiesValueChanged([
@@ -66,7 +76,7 @@ export class PageViewModel<
     return this._page;
   }
 
-  public addGhostPage() {
+  public addGhostPage = () => {
     if (this.isGhost) {
       this.page.unRegisterFunctionOnPropertiesValueChanged([
         "title",

testCafe/designer/drag-drop.ts

@@ -32,6 +32,9 @@ test("Drag Drop Toolbox Item and Empty Page", async (t) => {
 
   const questionsLength = await getQuestionsLength();
   await t.expect(questionsLength).eql(2);
+
+  const ghostPageRowsCount = newGhostPagePage.find(".svc-row").count;
+  await t.expect(ghostPageRowsCount).eql(0);
 });
 
 test("Drag Drop Question", async (t) => {