Mareo Code

       frmOptions formOptions = new frmOptions();

            // open form only if is not open already
            bool isFormOpen = false;

            // iterate through all open forms
            foreach (Form frm in Application.OpenForms)
            {
                if (frm is frmOptions)
                {
                    // open already so just bring it to the front
                    frm.BringToFront();
                    isFormOpen = true;
                    break;
                }
            }

            if (!isFormOpen)
                // not open so show it
                formOptions.Show();
            else
                formOptions.Dispose();