From 392d25eb39bda1d7ff2993500115dbd2173484cf Mon Sep 17 00:00:00 2001
From: Beka Westberg <bekawestberg@gmail.com>
Date: Tue, 18 Feb 2020 16:01:18 -0800
Subject: [PATCH 1/2] fix: Break breaking undo.

---
 blocks/loops.js   | 27 +++++++++++++--------------
 core/block_svg.js |  2 +-
 2 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/blocks/loops.js b/blocks/loops.js
index 57ef12aac..0163350d5 100644
--- a/blocks/loops.js
+++ b/blocks/loops.js
@@ -327,24 +327,23 @@ Blockly.Constants.Loops.CONTROL_FLOW_IN_LOOP_CHECK_MIXIN = {
   /**
    * Called whenever anything on the workspace changes.
    * Add warning if this flow block is not nested inside a loop.
-   * @param {!Blockly.Events.Abstract} _e Change event.
+   * @param {!Blockly.Events.Abstract} e Change event.
    * @this {Blockly.Block}
    */
-  onchange: function(_e) {
-    if (!this.workspace.isDragging || this.workspace.isDragging()) {
+  onchange: function(e) {
+    if (!this.workspace.isDragging || this.workspace.isDragging() ||
+        e.type != Blockly.Events.BLOCK_MOVE || e.blockId != this.id) {
       return;  // Don't change state at the start of a drag.
     }
-    if (Blockly.Constants.Loops.CONTROL_FLOW_IN_LOOP_CHECK_MIXIN
-        .getSurroundLoop(this)) {
-      this.setWarningText(null);
-      if (!this.isInFlyout) {
-        this.setEnabled(true);
-      }
-    } else {
-      this.setWarningText(Blockly.Msg['CONTROLS_FLOW_STATEMENTS_WARNING']);
-      if (!this.isInFlyout && !this.getInheritedDisabled()) {
-        this.setEnabled(false);
-      }
+    var enabled = Blockly.Constants.Loops.CONTROL_FLOW_IN_LOOP_CHECK_MIXIN
+        .getSurroundLoop(this);
+    this.setWarningText(enabled ? null :
+        Blockly.Msg['CONTROLS_FLOW_STATEMENTS_WARNING']);
+    if (!this.isInFlyout) {
+      var group = Blockly.Events.getGroup();
+      Blockly.Events.setGroup(e.group);
+      this.setEnabled(enabled);
+      Blockly.Events.setGroup(group);
     }
   }
 };
diff --git a/core/block_svg.js b/core/block_svg.js
index 65741cfe4..fe9815d6b 100644
--- a/core/block_svg.js
+++ b/core/block_svg.js
@@ -1180,7 +1180,7 @@ Blockly.BlockSvg.prototype.setDisabled = function(disabled) {
 Blockly.BlockSvg.prototype.setEnabled = function(enabled) {
   if (this.isEnabled() != enabled) {
     Blockly.BlockSvg.superClass_.setEnabled.call(this, enabled);
-    if (this.rendered) {
+    if (this.rendered && !this.getInheritedDisabled()) {
       this.updateDisabled();
     }
   }

From 5445cf4cf823a8dbbcae5f356776733ae5e6193e Mon Sep 17 00:00:00 2001
From: Beka Westberg <bekawestberg@gmail.com>
Date: Wed, 19 Feb 2020 14:40:28 -0800
Subject: [PATCH 2/2] Add comments to break block change listener.

---
 blocks/loops.js | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/blocks/loops.js b/blocks/loops.js
index 0163350d5..d6fb2f2f6 100644
--- a/blocks/loops.js
+++ b/blocks/loops.js
@@ -331,9 +331,13 @@ Blockly.Constants.Loops.CONTROL_FLOW_IN_LOOP_CHECK_MIXIN = {
    * @this {Blockly.Block}
    */
   onchange: function(e) {
+    // Don't change state if:
+    //   * It's at the start of a drag.
+    //   * It's not a move event.
+    //   * Or the moving block is not this block.
     if (!this.workspace.isDragging || this.workspace.isDragging() ||
         e.type != Blockly.Events.BLOCK_MOVE || e.blockId != this.id) {
-      return;  // Don't change state at the start of a drag.
+      return;
     }
     var enabled = Blockly.Constants.Loops.CONTROL_FLOW_IN_LOOP_CHECK_MIXIN
         .getSurroundLoop(this);
@@ -341,6 +345,7 @@ Blockly.Constants.Loops.CONTROL_FLOW_IN_LOOP_CHECK_MIXIN = {
         Blockly.Msg['CONTROLS_FLOW_STATEMENTS_WARNING']);
     if (!this.isInFlyout) {
       var group = Blockly.Events.getGroup();
+      // Makes it so the move and the disable event get undone together.
       Blockly.Events.setGroup(e.group);
       this.setEnabled(enabled);
       Blockly.Events.setGroup(group);