Merge pull request #3816 from NoelDeMartin/MOBILE-4362

MOBILE-4362: Fix Drag & Drop race condition

src/addons/qtype/ddimageortext/classes/ddimageortext.ts

@@ -12,7 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-import { CoreUtils } from '@services/utils/utils';
 import { CoreDom } from '@singletons/dom';
 import { CoreEventObserver } from '@singletons/events';
 import { CoreLogger } from '@singletons/logger';
@@ -148,7 +147,10 @@ export class AddonQtypeDdImageOrTextQuestion {
             }
         }
 
-        await CoreUtils.nextTick();
+        await CoreDom.waitToBeVisible(
+            this.container.querySelector<HTMLElement>('.ddarea') ??
+            this.container,
+        );
 
         // All drag items have been created, position them.
         this.repositionDragsForQuestion();

src/core/singletons/dom.ts

@@ -123,8 +123,12 @@ export class CoreDom {
      * @returns True if element is visible inside the DOM.
      */
     static isElementVisible(element: HTMLElement, checkSize = true): boolean {
-        if (checkSize && (element.clientWidth === 0 || element.clientHeight === 0)) {
-            return false;
+        if (checkSize) {
+            const dimensions = element.getBoundingClientRect();
+
+            if (dimensions.width === 0 || dimensions.height === 0) {
+                return false;
+            }
         }
 
         const style = getComputedStyle(element);