From 1faeaedebff1510a79ac24121be1836139c90575 Mon Sep 17 00:00:00 2001
From: jbooth88 <42254680+jbooth88@users.noreply.github.com>
Date: Wed, 19 Mar 2025 15:59:15 -0700
Subject: [PATCH] Fix issue #3819

This change prevents an issue where the AssociatedObject unexpectedly changes in an non thread-safe manner.
---
 .../Behaviors/TextBoxLineCountBehavior.cs                   | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/MaterialDesignThemes.Wpf/Behaviors/TextBoxLineCountBehavior.cs b/src/MaterialDesignThemes.Wpf/Behaviors/TextBoxLineCountBehavior.cs
index 582294a800..6952856690 100644
--- a/src/MaterialDesignThemes.Wpf/Behaviors/TextBoxLineCountBehavior.cs
+++ b/src/MaterialDesignThemes.Wpf/Behaviors/TextBoxLineCountBehavior.cs
@@ -12,10 +12,10 @@ public class TextBoxLineCountBehavior : Behavior<TextBox>
 
     private void UpdateAttachedProperties()
     {
-        if (AssociatedObject != null)
+        if (AssociatedObject is { } associatedObject)
         {
-            AssociatedObject.SetCurrentValue(TextFieldAssist.TextBoxLineCountProperty, AssociatedObject.LineCount);
-            AssociatedObject.SetCurrentValue(TextFieldAssist.TextBoxIsMultiLineProperty, AssociatedObject.LineCount > 1);
+            associatedObject.SetCurrentValue(TextFieldAssist.TextBoxLineCountProperty, associatedObject.LineCount);
+            associatedObject.SetCurrentValue(TextFieldAssist.TextBoxIsMultiLineProperty, associatedObject.LineCount > 1);
         }
     }