Draggable: Fix a bug when dragging into nested sortables there are duplicated placeholders. Fixes #7777 - Draggable and Nested Sortables bug.

Author: zhizhangchen

ui/jquery.ui.draggable.js

@@ -571,13 +571,29 @@ $.ui.plugin.add("draggable", "connectToSortable", {
 
 		$.each(inst.sortables, function(i) {
 
+			var innermostIntersecting = false;
+			var thisSortable = this;
 			//Copy over some variables to allow calling the sortable's native _intersectsWith
 			this.instance.positionAbs = inst.positionAbs;
 			this.instance.helperProportions = inst.helperProportions;
 			this.instance.offset.click = inst.offset.click;
 
 			if(this.instance._intersectsWith(this.instance.containerCache)) {
+				innermostIntersecting = true;
+				$.each(inst.sortables, function () {
+					this.instance.positionAbs = inst.positionAbs;
+					this.instance.helperProportions = inst.helperProportions;
+					this.instance.offset.click = inst.offset.click;
+					if  (this != thisSortable
+						&& this.instance._intersectsWith(this.instance.containerCache)
+						&& $.ui.contains(thisSortable.instance.element[0], this.instance.element[0]))
+						innermostIntersecting = false;
+						return innermostIntersecting;
+				});
+			}
+
 
+			if(innermostIntersecting) {
 				//If it intersects, we use a little isOver variable and set it once, so our move-in stuff gets fired only once
 				if(!this.instance.isOver) {