如何保留所有集中的表格？

Question

I've an application that use two forms: Form1 (main) and Form2 (secondary). I show the Form2 with the following code:

Form2 frm = new Form2();
frm.TopMost = true;
frm.Show();

When the Form2 is visible, it hasn't the focus. How can I do the focus at the Form2 and keep the focus at the Form1? Sorry for my bad english!

Answer 1

try bellow code within MDI Parent Form (Main Form)

private Form2 _form2;

#region UtilOpenForm
    /// <summary>
    /// UtilOpenForm
    /// </summary>
    /// <param name="appContainer"></param>
    /// <param name="childForm"></param>
    private void UtilOpenForm(Form appContainer, Form childForm)
    {
        this.Cursor = Cursors.WaitCursor;
        if (childForm == null)
        {
            throw new ArgumentNullException("childForm");
        }
        childForm.MdiParent = appContainer;
        childForm.StartPosition = FormStartPosition.CenterScreen;
        childForm.MaximizeBox = false;
        childForm.MinimizeBox = false;
        childForm.Closed += new EventHandler(childForm_Closed);
        childForm.Show();
        this.Cursor = Cursors.Default;
    }

Now from Button / Menu click within MDI Parent

    if (_form2 == null)
        {
            UtilOpenForm(this, _form2 = new Form2());
        }

Now child form close Function within MDI Parent

   #region childForm_Closed
    /// <summary>
    /// 
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    private void childForm_Closed(object sender, EventArgs e)
    {
        if (sender.GetType() == typeof(Form2))
        {
            _form2.Dispose();

            if (_form2 != null)
            {
                _form2 = null;
            }
        }