From 0323a873d5902a0c1803f304c5799cc8e7ffab6d Mon Sep 17 00:00:00 2001
From: Dong Bin <popmessiah@hotmail.com>
Date: Tue, 8 Jul 2025 15:18:41 +0800
Subject: [PATCH] feat: add generic constraint to fix null reference issue.

---
 src/Ursa/Common/VisualHelpers.cs | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/Ursa/Common/VisualHelpers.cs b/src/Ursa/Common/VisualHelpers.cs
index 37195ac..511a3d2 100644
--- a/src/Ursa/Common/VisualHelpers.cs
+++ b/src/Ursa/Common/VisualHelpers.cs
@@ -1,13 +1,14 @@
 using Avalonia;
+using Avalonia.Controls;
 using Avalonia.VisualTree;
 
 namespace Ursa.Common;
 
 public static class VisualHelpers
 {
-    public static T? GetContainerFromEventSource<T>(this Visual? source)
+    public static T? GetContainerFromEventSource<T>(this Visual? source) where T: Control
     {
-        var item = source.GetSelfAndVisualAncestors().OfType<T>().FirstOrDefault();
+        var item = source?.GetSelfAndVisualAncestors().OfType<T>().FirstOrDefault();
         return item;
     }
 }
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