From 6bc8126591110aaf3b5feae45386eeaca0223df5 Mon Sep 17 00:00:00 2001
From: Max Hoffmann <tsov@me.com>
Date: Fri, 29 Sep 2017 15:09:22 -0400
Subject: [PATCH] Fixing swappable swap logic

---
 src/swappable.js | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/swappable.js b/src/swappable.js
index 079b171..9844c7b 100644
--- a/src/swappable.js
+++ b/src/swappable.js
@@ -51,19 +51,20 @@ export default class Swappable {
   }
 
   _onDragOver(event) {
-    if (event.over === event.source) {
-      return;
-    }
-
-    if (event.canceled()) {
+    if (event.over === event.source || event.canceled()) {
       return;
     }
 
+    // swap originally swapped element back
     if (this.lastOver && this.lastOver !== event.over) {
       swap(this.lastOver, event.source);
     }
 
-    this.lastOver = event.over;
+    if (this.lastOver === event.over) {
+      this.lastOver = null;
+    } else {
+      this.lastOver = event.over;
+    }
 
     swap(event.source, event.over);