From 90f6832d06bf14c382087407eafbc69d3bfb2921 Mon Sep 17 00:00:00 2001
From: Rachel Fenichel <fenichel@google.com>
Date: Fri, 15 Feb 2019 12:43:45 -0800
Subject: [PATCH] Fix insertion marker flickering on value inputs (PR #2295)

Merge from rachel-fenichel/bugfix/2255
---
 core/connection.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/core/connection.js b/core/connection.js
index 6e978dedc..76ccb40b9 100644
--- a/core/connection.js
+++ b/core/connection.js
@@ -392,7 +392,9 @@ Blockly.Connection.prototype.isConnectionAllowed = function(candidate) {
     case Blockly.OUTPUT_VALUE: {
       // Don't offer to connect an already connected left (male) value plug to
       // an available right (female) value plug.
-      if (candidate.isConnected() || this.isConnected()) {
+      if ((candidate.isConnected() &&
+          !candidate.targetBlock().isInsertionMarker()) ||
+          this.isConnected()) {
         return false;
       }
       break;