Ticket #13524: 13524.patch

src/wp-admin/js/widgets.js

@@ -135 +135 @@
                                         // Prevents jumping when dragging a widget from an open sidebar to a closed sidebar below.
                                         height = ui.item.hasClass('ui-draggable') ? $this.height() : 1 + $this.height();
                                         $this.css( 'min-height', height + 'px' );
+                                } else {
+                                        $wrap.removeClass('closed');
                                 }
                         },