From ccfb61ca9c4878bf1c8cfbed21d9ed5d1a9da4d5 Mon Sep 17 00:00:00 2001
From: Joachim Marder <joachim.marder@outlook.com>
Date: Thu, 13 Apr 2023 15:24:16 +0200
Subject: [PATCH] Fixed issue #1187

---
 Source/VirtualTrees.StyleHooks.pas | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Source/VirtualTrees.StyleHooks.pas b/Source/VirtualTrees.StyleHooks.pas
index 8213b7223..0e06a6803 100644
--- a/Source/VirtualTrees.StyleHooks.pas
+++ b/Source/VirtualTrees.StyleHooks.pas
@@ -195,8 +195,6 @@ procedure TVclStyleScrollBarsHook.CalcScrollBarsRect();
 constructor TVclStyleScrollBarsHook.Create(AControl: TWinControl);
 begin
   inherited;
-  InitScrollBars;
-
   {$ifdef NOT_USE_VCL_STYLEHOOK}
   VertSliderState := tsThumbBtnVertNormal;
   VertUpState := tsArrowBtnUpNormal;
@@ -244,6 +242,9 @@ procedure TVclStyleScrollBarsHook.UpdateScroll;
   PaddingSize: Integer;
   BorderSize: Integer;
 begin
+  if VertScrollWnd = nil then
+     InitScrollBars();
+
   HeaderHeight := 0;
   if (hoVisible in TBaseVirtualTree(Control).Header.Options) then
     Inc(HeaderHeight, TBaseVirtualTree(Control).Header.Height);