Control control = ActiveControl;axAcroPDF1.LoadFile(@"..\..\test.pdf");if (control == null) return;Thread thread = new Thread(new ThreadStart(delegate() {while (true) {Thread.Sleep(300);bool focused = true;Invoke((MethodInvoker)delegate() {focused = control.Focused;});if (!focused){Invoke((MethodInvoker)delegate() {control.Focus();});break;}}}));thread.Start();