Window rendering error after calling CallWindowProc and DefWindowProc

[Pixelmak]

I am trying to get Windows messages via WndCallback in Windows 11. But, after receiving the message, the window is not rendered normally. What am I doing wrong? (Screen in Attachment)

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode delphi}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, Forms, Controls, Graphics, Dialogs, StdCtrls, Windows;
9.  
10. type
11.  
12.   { TForm1 }
13.  
14.   TForm1 = class(TForm)
15.     Button1: TButton;
16.     procedure Button1Click(Sender: TObject);
17.     procedure FormCreate(Sender: TObject);
18.   private
19.  
20.   public
21.  
22.   end;
23.  
24.   function WndCallback(Ahwnd: HWND; uMsg: UINT; wParam: WParam; lParam: LParam): LRESULT; stdcall;
25.  
26. var
27.   Form1: TForm1;
28.   PrevWndProc:windows.WNDPROC;
29.  
30. implementation
31.  
32. function WndCallback(Ahwnd: HWND; uMsg: UINT; wParam: WParam; lParam: LParam
33.   ): LRESULT; stdcall;
34. begin
35.   result := CallWindowProc(PrevWndProc , Ahwnd, uMsg, WParam, LParam);
36. end;
37.  
38. {$R *.lfm}
39.  
40. { TForm1 }
41.  
42. procedure TForm1.FormCreate(Sender: TObject);
43. begin
44.   PrevWndProc := Windows.WNDPROC(SetWindowLongPtr(Self.Handle, GWL_WNDPROC, PtrUInt(@WndCallback)));
45. end;
46.  
47. procedure TForm1.Button1Click(Sender: TObject);
48. begin
49.   writeln('Button clicked');
50. end;
51.  
52. end.
53.  

[Pixelmak]

Oh, I'm sorry. This code works now. I don’t know for what reason this error occurred.

Perhaps the reason was that I used DefWindowProc instead of CallWindowProc