How to add mdi child instance as a menuitem -2

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C#

controls

In my application: on my main page I have a menu strip containing menu items File and Windows. The File menu contains two menu items File1 and File2. When I click on File1 a new form will open and a menu item f1 is added under windows menu.

Its just like windows menu in Ms Word. Now I am trying to remove menu item f1 when I close the form. What do I do for this? Please help me. Also, I am trying to set a check on the menu item if the form is selected.

See code below:

Form1(MdiContainer)

private void tmFile1_Click(object sender, EventArgs e)
        {
            frmFile1 ft1 = new fromTrail2();
            ft1.MdiParent = this;
            ft1.MS = msFile;
            ToolStripMenuItem tmTrail1 = new ToolStripMenuItem();
            tmTrail1.Name = ft1.Name;
            tmTrail1.Text = "Trail2";
            ft1.STMI = tmTrail1;
            tmForms.DropDownItems.Add(ft1.STMI);
            ft1.Show();
            WinMenu.Add(ft1, tmTrail1);
        }

frmFile1

private MenuStrip MenuSrtp;
        private ToolStripMenuItem stmi;
        public ToolStripMenuItem STMI
        {
            get
         {
                return stmi;
            }
            set
            {
                stmi = value;
            }
        }
        public MenuStrip MS
        {
            set
            {
                MenuSrtp = value;
            }
            get
            {
                return MenuSrtp;
            }
        }

        private void frmTrail1_Closing(object sender, System.ComponentModel.CancelEventArgs e)
        {
            MS.Items.Remove(stmi);
        }