One possible solution I think: 1. MainmForm.ShowTitle = True 2. Hide for example: procedure TMainmForm.UnimFormCreate(Sender: TObject); begin Self.WebForm.JSInterface.JSCall('owner.titlebar.hide', []); end; 3. Show: procedure TMainmForm.UnimButton2Click(Sender: TObject); begin Self.WebForm.JSInterface.JSCall('owner.titlebar.show', []); end;