From 5d6cad752d14df1c0ca7481442e28c343645a5eb Mon Sep 17 00:00:00 2001
From: michl <michl@lazarus-ide.org>
Date: Thu, 6 May 2021 20:23:34 +0000
Subject: [PATCH] LCL: Fixed TForm.AutoScroll does not turn off scrollbars if
 UNCHECKED while scrollbars are showing. Issue #38856

git-svn-id: trunk@65089 -
---
 lcl/forms.pp                        |  1 +
 lcl/include/scrollingwincontrol.inc | 23 ++++++++++++++++++++++-
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/lcl/forms.pp b/lcl/forms.pp
index e436715612..d61c91ff8b 100644
--- a/lcl/forms.pp
+++ b/lcl/forms.pp
@@ -160,6 +160,7 @@ type
     FIsUpdating: Boolean;
     procedure SetHorzScrollBar(Value: TControlScrollBar);
     procedure SetVertScrollBar(Value: TControlScrollBar);
+    procedure HideScrollbars;
   protected
     class procedure WSRegisterClass; override;
     procedure AlignControls(AControl: TControl; var ARect: TRect); override;
diff --git a/lcl/include/scrollingwincontrol.inc b/lcl/include/scrollingwincontrol.inc
index 33dd74ede9..139d190ced 100644
--- a/lcl/include/scrollingwincontrol.inc
+++ b/lcl/include/scrollingwincontrol.inc
@@ -13,7 +13,10 @@ procedure TScrollingWinControl.SetAutoScroll(Value: Boolean);
 begin
   if FAutoScroll = Value then Exit;
   FAutoScroll := Value;
-  UpdateScrollBars;
+  if Value then
+    UpdateScrollBars
+  else
+    HideScrollbars;
 end;
 
 procedure TScrollingWinControl.CreateWnd;
@@ -142,6 +145,24 @@ begin
   FVertScrollbar.Assign(Value);
 end;
 
+procedure TScrollingWinControl.HideScrollbars;
+begin
+  if Assigned(FHorzScrollBar) and FHorzScrollBar.HandleAllocated then
+  begin
+    ShowScrollBar(FHorzScrollBar.ControlHandle, SB_Horz, False);
+    FHorzScrollBar.Range := 0;
+    FHorzScrollBar.Page := 80;
+    FHorzScrollBar.Position := 0;
+  end;
+  if Assigned(FVertScrollBar) and FVertScrollBar.HandleAllocated then
+  begin
+    ShowScrollBar(FVertScrollBar.ControlHandle, SB_Vert, False);
+    FVertScrollBar.Range := 0;
+    FVertScrollBar.Page := 80;
+    FVertScrollBar.Position := 0;
+  end;
+end;
+
 procedure TScrollingWinControl.WMSize(var Message: TLMSize);
 var
   NewState: TWindowState;