From d4a4476f473ebb2e36a1cd97451cab7076e7bc02 Mon Sep 17 00:00:00 2001
From: Ilya Kirillov <ilya.kirillov@onlyoffice.com>
Date: Fri, 10 Oct 2025 17:54:37 +0300
Subject: [PATCH] Fix bug #77520

Don't treat complex field with out ffData as a form field
---
 word/Editor/Paragraph/ComplexField.js         | 7 ++++++-
 word/Editor/Paragraph/ComplexFields/ffdata.js | 4 ++++
 word/Editor/Run.js                            | 2 +-
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/word/Editor/Paragraph/ComplexField.js b/word/Editor/Paragraph/ComplexField.js
index 3e9fb11bf2..3b77eda29b 100644
--- a/word/Editor/Paragraph/ComplexField.js
+++ b/word/Editor/Paragraph/ComplexField.js
@@ -2093,7 +2093,12 @@ CComplexField.prototype.IsFormFieldEnabled = function()
 };
 CComplexField.prototype.IsFormCheckBox = function()
 {
-	return this.CheckType(AscWord.fieldtype_FORMCHECKBOX);
+	if (!this.CheckType(AscWord.fieldtype_FORMCHECKBOX))
+		return false;
+	
+	let beginChar = this.GetBeginChar();
+	let ffData    = beginChar ? beginChar.GetFFData() : null;
+	return ffData && ffData.isCheckBox();
 };
 CComplexField.prototype.ToggleFormCheckBox = function()
 {
diff --git a/word/Editor/Paragraph/ComplexFields/ffdata.js b/word/Editor/Paragraph/ComplexFields/ffdata.js
index 186e9437f9..a1b25a90ef 100644
--- a/word/Editor/Paragraph/ComplexFields/ffdata.js
+++ b/word/Editor/Paragraph/ComplexFields/ffdata.js
@@ -200,6 +200,10 @@
 		writer.WriteLong(flags);
 		writer.Seek(endPos);
 	};
+	FFData.prototype.isCheckBox = function()
+	{
+		return (!!this.checkBox);
+	};
 	FFData.fromBinary = function(reader)
 	{
 		let ffData = new FFData();
diff --git a/word/Editor/Run.js b/word/Editor/Run.js
index 9df54e968c..c5b0d0699e 100644
--- a/word/Editor/Run.js
+++ b/word/Editor/Run.js
@@ -4861,7 +4861,7 @@ ParaRun.prototype.Recalculate_Range = function(PRS, ParaPr, Depth)
 							}
 							isVisualFieldChar = true;
 						}
-						else if (oInstruction && AscWord.fieldtype_FORMCHECKBOX === oInstruction.GetType())
+						else if (oComplexField.IsFormCheckBox())
 						{
 							isVisualFieldChar = true;
 							Item.SetFormCheckBox(true);