VSTO Excel Workbook got focus event

[FishGuy]

In my workbook I can only see the initialize, startup and shutdown events.
Is it possible to perform an action when the workbook gets the focus?

[FishGuy]

I tried this in the sheet code behind and whilst the internal startup code is run the Activate_Event never gets called from startup or on receiving focus.

private void InternalStartup()
        {
            this.ActivateEvent += new Microsoft.Office.Interop.Excel.DocEvents_ActivateEventHandler(this.Activate_Event);

        }

        private void Activate_Event()
        {
            Globals.ThisWorkbook.Application.SendKeys("%RPT{RETURN}", true);

        }