Droppable: Added dragStart and dragStop to ddmanager and call them from draggable to recalculate droppable positions after a drag causes a scroll. Fixes #5003 - Scroll on Droppable Demo Breaks Demo

(cherry picked from commit 67bd872)

Author: kborchers

ui/jquery.ui.draggable.js

@@ -163,6 +163,10 @@ $.widget("ui.draggable", $.ui.mouse, {
 
 		this.helper.addClass("ui-draggable-dragging");
 		this._mouseDrag(event, true); //Execute the drag once - this causes the helper not to be visible before getting its correct position
+		
+		//If the ddmanager is used for droppables, inform the manager that dragging has started (see #5003)
+		if ( $.ui.ddmanager ) $.ui.ddmanager.dragStart(this, event);
+		
 		return true;
 	},
 
@@ -229,6 +233,9 @@ $.widget("ui.draggable", $.ui.mouse, {
 			}); //Remove frame helpers
 		}
 
+		//If the ddmanager is used for droppables, inform the manager that dragging has stopped (see #5003)
+		if( $.ui.ddmanager ) $.ui.ddmanager.dragStop(this, event);
+		
 		return $.ui.mouse.prototype._mouseUp.call(this, event);
 	},
 

ui/jquery.ui.droppable.js

@@ -238,6 +238,12 @@ $.ui.ddmanager = {
 		return dropped;
 
 	},
+	dragStart: function( draggable, event ) {
+		//Listen for scrolling so that if the dragging causes scrolling the position of the droppables can be recalculated (see #5003)
+		draggable.element.parentsUntil( "body" ).bind( "scroll.droppable", function() {
+			if( !draggable.options.refreshPositions ) $.ui.ddmanager.prepareOffsets( draggable, event );
+		});
+	},
 	drag: function(draggable, event) {
 
 		//If you have a highly dynamic page, you might try this option. It renders positions every time you move the mouse.
@@ -279,6 +285,11 @@ $.ui.ddmanager = {
 			}
 		});
 
+	},
+	dragStop: function( draggable, event ) {
+		draggable.element.parentsUntil( "body" ).unbind( "scroll.droppable" );
+		//Call prepareOffsets one final time since IE does not fire return scroll events when overflow was caused by drag (see #5003)
+		if( !draggable.options.refreshPositions ) $.ui.ddmanager.prepareOffsets( draggable, event );
 	}
 };