主窗口通用泛型打开不同子窗口

private void OpenForm<T>(T t, string caption) where T : System.Type
        {

            Form form = Application.OpenForms[t.Name];
            if (form == null)
            {
                object itemForm = System.Activator.CreateInstance(t);
                BaseForm frm = itemForm as BaseForm;
                frm.Text = caption;
                frm.MdiParent = this;
                frm.Show();
            }
            else
            {
                form.Activate();
            }
        }