C#

bool found = false;
foreach (Form f in this.MdiChildren)
{
    if (f.Text == "RibbonForm1")
    {
        found = true;
        f.TopMost = true;
    }
}
if (!found)
{
    RibbonForm1 frm = new RibbonForm1();
    frm.MdiParent = this;
    frm.Show();
}

<font><font>   public class FormpoolClass
    {
        private Dictionary< string, Form > formPool = new Dictionary< string, form=>();

        public class CustomForm : Form
        {

        }

        public formType GetForm<formType>(string form_id) where formType : Form
        {
            if (this.formPool.ContainsKey(form_id))             // check out if we have a reference to the form
            {
                if (formPool[form_id] != null && !formPool[form_id].IsDisposed)
                    return formPool[form_id] as formType;            // if so, return it
                else formPool.Remove(form_id);
            }

            formType ret = null;
            try
            {
                ret = Activator.CreateInstance<formType>();     // not there, so create it
            }
            catch (Exception e)
            {
                Console.WriteLine(e.ToString());
            }

            Debug.Assert(ret != null);
            return ret;
        }
    }

    public class Test
    {
        public void dotest()
        {
            FormpoolClass fpc = new FormpoolClass();
            CustomForm f = fpc.GetForm<customform&rt;("myform_id");
        }
    }
</customform></font></font>

MyForm form = new MyForm();
form.Parent = this;
form.Show();