From d767c1dceea3f1e83dca45695ab992eb76b2afa2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C5=BDeljan=20Rikalo?= <zeljko@lazarus-ide.org>
Date: Fri, 3 Sep 2021 20:13:15 +0200
Subject: [PATCH] Qt5: Fixed AV when changing TListView.ViewStyle in design
 time. Issue #39353

(cherry picked from commit 63ca7a9aceb300e68f9ebf0b9cfa79e041e63a7e)
---
 lcl/interfaces/qt5/qtwscomctrls.pp | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/lcl/interfaces/qt5/qtwscomctrls.pp b/lcl/interfaces/qt5/qtwscomctrls.pp
index 4d62c0d8ec..4770b07354 100644
--- a/lcl/interfaces/qt5/qtwscomctrls.pp
+++ b/lcl/interfaces/qt5/qtwscomctrls.pp
@@ -841,6 +841,13 @@ begin
     exit(0);
 
   QtTreeWidget := TQtTreeWidget(ALV.Handle);
+
+  {Issue #39353.Such scenario happens only when SetStyle() calls RecreateWnd
+   while designing control.Default width for TListColumn is 50,
+   unfortunatelly it''s hardcoded in listcolumn.inc.}
+  if (csDesigning in ALV.ComponentState) and (QtTreeWidget.ColCount <> ALV.ColumnCount) then
+    exit(50);
+
   Result := QtTreeWidget.ColWidth[AIndex];
 end;