[Cesar82]

@Sergey3695, your script example.

// need for SetTaskBar*
SetupHandle(FindWindowByClassName('TApplication')) ;
//

I don't know if this is the best way to get the handle of the taskbar button.
It may be possible to get the handle of another Inno Setup application if run at the same time (I'm not sure).

I think this is the most correct way to avoid getting the handle of another instance of the Inno Setup installer.

const
  GWL_HWNDPARENT = (-8);

function GetWindowLong(hWnd, nIndex: Integer): Longint;
  external 'GetWindowLongW@user32 stdcall';

procedure InitializeWizard();
begin
  ExtractTemporaryFile('wintb.dll');
// need for SetTaskBar*
  SetupHandle(GetWindowLong(MainForm.Handle, GWL_HWNDPARENT));
//
//...