procedure SunkenButton(Bttn: TButtonControl; versunken: boolean); 
begin 
  if versunken then 
    SetWindowLong(Bttn.Handle, GWL_EXSTYLE, WS_EX_CLIENTEDGE) else 
    SetWindowLong(Bttn.Handle, GWL_EXSTYLE, WS_EX_WINDOWEDGE); 
  SetWindowPos(Bttn.Handle, HWND_TOP, Bttn.left, Bttn.top, 
    Bttn.width, Bttn.height, SWP_FRAMECHANGED); 
end; 
 
 
// Beispielaufrufe 
 

// versenken
procedure TForm1.Button1Click(Sender: TObject); 
begin 
  SunkenButton(Button3, true); 
  SunkenButton(Button4, true); 
end; 
 
// normal
procedure TForm1.Button2Click(Sender: TObject); 
begin 
  SunkenButton(Button3, false); 
  SunkenButton(Button4, false); 
end;