identificar evento de tipo Postback

public static Control GetPostBackControl(Page page)
{
Control control = null;
string ctrlname = page.Request.Params.Get("__EVENTTARGET");
if (ctrlname != null && ctrlname != string.Empty)
{
    control = page.FindControl(ctrlname);
}
else
{
    foreach (string ctl in page.Request.Form)
    {
	    Control c = page.FindControl(ctl);
	    if (c is System.Web.UI.WebControls.Button)
	    {
		    control = c;
		    break;
	    }
    }
}
return control;
}