From 38d47de87b8835e5e52ffb76071d774b859a95a2 Mon Sep 17 00:00:00 2001
From: Maxim Ganetsky <maxim@lazarus-ide.org>
Date: Sun, 25 May 2025 22:46:48 +0300
Subject: [PATCH] LCL: Do not try to access a method of nil AControl in class
 procedure TDockHeader.PerformMouseDown, fixes crashes in some cases. Issue
 #41675, hint by Hans vB.

---
 lcl/ldocktree.pas | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lcl/ldocktree.pas b/lcl/ldocktree.pas
index 86be66cc0d..5e9b6a1943 100644
--- a/lcl/ldocktree.pas
+++ b/lcl/ldocktree.pas
@@ -504,6 +504,8 @@ end;
 class procedure TDockHeader.PerformMouseDown(AControl: TControl;
   APart: TLazDockHeaderPart);
 begin
+  if AControl=nil then
+    exit;
   case APart of
     ldhpAll, ldhpCaption:
       // mouse down on not buttons => start drag