From 5c8ff88587f85bf6b756fbffc3ae32daf5039bbf Mon Sep 17 00:00:00 2001
From: rachel-fenichel <fenichel@google.com>
Date: Tue, 5 Apr 2016 16:13:19 -0700
Subject: [PATCH] Keep a list of connections that are being dragged

---
 core/block_svg.js  |  8 ++++++++
 core/blockly.js    |  2 ++
 core/connection.js | 11 ++---------
 3 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/core/block_svg.js b/core/block_svg.js
index efcacab5c..86c1ec94e 100644
--- a/core/block_svg.js
+++ b/core/block_svg.js
@@ -791,8 +791,11 @@ Blockly.BlockSvg.prototype.setDragging_ = function(adding) {
     group.translate_ = '';
     group.skew_ = '';
     this.addDragging();
+    Blockly.draggingConnections_ =
+        Blockly.draggingConnections_.concat(this.getConnections_(true));
   } else {
     this.removeDragging();
+    Blockly.draggingConnections_ = [];
   }
   // Recurse through all blocks attached under this one.
   for (var i = 0; i < this.childBlocks_.length; i++) {
@@ -854,6 +857,11 @@ Blockly.BlockSvg.prototype.onMouseMove_ = function(e) {
     // Check to see if any of this block's connections are within range of
     // another block's connection.
     var myConnections = this.getConnections_(false);
+    // Also check the last connection on this stack
+    var lastOnStack = this.lastConnectionInStack_();
+    if (lastOnStack && lastOnStack != this.nextConnection) {
+      myConnections.push(lastOnStack);
+    }
     var closestConnection = null;
     var localConnection = null;
     var radiusConnection = Blockly.SNAP_RADIUS;
diff --git a/core/blockly.js b/core/blockly.js
index 85d311e6d..109c694ff 100644
--- a/core/blockly.js
+++ b/core/blockly.js
@@ -82,6 +82,8 @@ Blockly.highlightedConnection_ = null;
  */
 Blockly.localConnection_ = null;
 
+Blockly.draggingConnections_ = [];
+
 /**
  * Contents of the local clipboard.
  * @type {Element}
diff --git a/core/connection.js b/core/connection.js
index 89b4aef27..549cf3f10 100644
--- a/core/connection.js
+++ b/core/connection.js
@@ -400,15 +400,8 @@ Blockly.Connection.prototype.isConnectionAllowed = function(candidate,
   }
 
   // Don't let blocks try to connect to themselves or ones they nest.
-  var targetSourceBlock = candidate.getSourceBlock();
-  var sourceBlock = this.sourceBlock_;
-  if (targetSourceBlock && sourceBlock) {
-    do {
-      if (sourceBlock == targetSourceBlock) {
-        return false;
-      }
-      targetSourceBlock = targetSourceBlock.getParent();
-    } while (targetSourceBlock);
+  if (Blockly.draggingConnections_.indexOf(candidate) != -1) {
+    return false;
   }
 
   return true;