Pull request #7998: REPORT-66947 拖拽拖出可拖拽区域的时候，会导致下次拖拽新组件受到上次拖拽缓存影响的问题

Merge in DESIGN/design from ~FANGLEI/design:final/11.0 to final/11.0

* commit '6ddf7a3e6115907e1423b042fcd8b8da67b3aca3':
  REPORT-66939
  REPORT-66947
  REPORT-66947 拖拽拖出可拖拽区域的时候，没有及时清理内存里残留的上次dropTarget对象，需要清理一下

designer-form/src/main/java/com/fr/design/mainframe/FormDesigner.java

@@ -1248,7 +1248,7 @@ public class FormDesigner extends TargetComponent<Form> implements TreeSelection
      * @param currentDragEvent
      */
     public void startDraggingNewWidget(XCreator xCreator, MouseEvent startDragEvent, MouseEvent currentDragEvent) {
-        if (currentDragEvent == null || this.getDropTarget() != null) {
+        if (currentDragEvent == null) {
             return;
         }
 
@@ -1270,7 +1270,7 @@ public class FormDesigner extends TargetComponent<Form> implements TreeSelection
      * @param currentDragEvent
      */
     public void startDraggingFormWidget(XCreator xCreator, MouseEvent startDragEvent, MouseEvent currentDragEvent) {
-        if (currentDragEvent == null || this.getDropTarget() != null) {
+        if (currentDragEvent == null) {
             return;
         }
         backUpCreator(xCreator);
@@ -1318,7 +1318,14 @@ public class FormDesigner extends TargetComponent<Form> implements TreeSelection
         DraggingModel model = this.draggingModel;
         MouseEvent dragEvent = model.getCurrentDragEvent();
         XCreator hotspot = this.getComponentAt(dragEvent.getX(), dragEvent.getY());
-        return XCreatorUtils.getHotspotContainer(hotspot);
+        XLayoutContainer container = XCreatorUtils.getHotspotContainer(hotspot);
+        XLayoutContainer topLayout = container.getTopLayout();
+        // REPORT-66939 Tab比较特殊，它是又多个LayoutContainer组成，直接返回container会导致误判，需要先找到最上层topLayout，取其父layout才是正确结果
+        if (topLayout != null && container != topLayout) {
+            return (XLayoutContainer) topLayout.getParent();
+        } else {
+            return container;
+        }
     }
 
     /**