// Adding overlay icon to all used imagelists
//   Small (16)
ImageList := GetImageListSH(SHIL_SMALL)
__AddNewOverlayIcon(16);
//   Large (32)
ImageList := GetImageListSH(SHIL_LARGE)
__AddNewOverlayIcon(32);
//   Extra Large (48)
ImageList := GetImageListSH(SHIL_EXTRALARGE);
__AddNewOverlayIcon(48);
//   Jumbo (256x256)
if RunningOnWinVistaAndHigher  and
  Succeeded(SHGetImageList(SHIL_JUMBO, IID_IImageList, Pointer(ImageList))) then
__AddNewOverlayIcon(256);

 procedure __AddNewOverlayIcon(const IconListSize: Integer);
 var
   IconList: TSxIconList;
   OurSysIconIndex: Integer;
   tmpHIcon: HICON;
 begin
   Lock;
   try
     tmpHIcon := IconList.GetHIcon(OurOverlayIndex);
     if tmpHIcon <> 0 then
     try
       OurSysIconIndex := ImageList_AddIcon(ImageList, tmpHIcon);
       //!! При IconListSize = 255 ImageList_AddIcon возращает -1
       if OurSysIconIndex >= 0 then
       begin
 //
       end;
     finally
       DestroyIcon(tmpHIcon);
     end;
   finally
     UnLock;
   end;
 end;

function GetImageListSH(SHIL_FLAG:Cardinal): HIMAGELIST;
type
 _SHGetImageList = function (iImageList: integer; const riid: TGUID; var ppv: Pointer): hResult; stdcall;
var
 Handle: THandle;
 SHGetImageList: _SHGetImageList;
begin
 Result:= 0;
 Handle:= LoadLibrary('Shell32.dll');
 if Handle<>S_OK then
 try
   SHGetImageList:=GetProcAddress(Handle, PChar(727));
   if Assigned(SHGetImageList) and (Win32Platform=VER_PLATFORM_WIN32_NT) then
     SHGetImageList(SHIL_FLAG, IID_IImageList, Pointer(Result));
 finally
   FreeLibrary(Handle);
 end;
end;

procedure TFmMain.bTestClick(Sender: TObject);
var
 ImageList: HIMAGELIST;
 Ico: TIcon;
 Res: Integer;
begin
 if odPicture.Execute then
 begin
   ImageList := GetImageListSH(SHIL_JUMBO);
   Ico := TIcon.Create;
   try
     ico.LoadFromFile(odPicture.FileName);
     Res := ImageList_AddIcon(ImageList,Ico.Handle);
     ShowMessage(IntToStr(Res));  //Res always equal -1
   finally
     ico.Free;
   end;
 end;
end;