1using System;
2using System.Collections.Generic;
3using System.ComponentModel;
4using System.Data;
5using System.Drawing;
6using System.Text;
7using System.Windows.Forms;
8
9namespace WindowsApplication2
10{
11    public partial class Form1 : Form
12    {
13        public Form1()
14        {
15            InitializeComponent();
16
17        }
18
19        private void toolStripButton1_Click(object sender, EventArgs e)
20        {
21            Form2 form = new Form2();
22            ToolStripMenuItem item = new ToolStripMenuItem((this.MdiChildren.Length + 1).ToString());
23            toolStripDropDownButton1.DropDownItems.Add(item);
24            form.MdiParent = this;
25            form.Text = item.Text;
26            ToolMenuItemEven rm = new ToolMenuItemEven(this, form, item);
27            form.Show();
28        }
29    }
30
31    public class ToolMenuItemEven
32    {
33        private Form form = null;
34        ToolStripMenuItem item = null;
35        private Form1 mdiForm;
36
37        public ToolMenuItemEven(Form1 mdiForm, Form fm, ToolStripMenuItem item)
38        {
39            this.mdiForm = mdiForm;
40            this.form = fm;
41            this.item = item;
42            fm.Disposed += new EventHandler(RemoveItem);
43            item.Click += new EventHandler(ItemClick);
44            ItemClearCheck();
45            item.Checked = true;
46            item = null;
47            fm = null;
48        }
49
50        private void RemoveItem(object obj, EventArgs e)
51        {
52            if (mdiForm != null)
53            {
54                mdiForm.toolStripDropDownButton1.DropDownItems.Remove(item);
55            }
56        }
57
58        private void ItemClick(object sender, EventArgs e)
59        {
60            if (form != null && item != null)
61            {
62                form.Activate();
63                ItemClearCheck();
64                item.Checked = true;
65            }
66        }
67
68        private void ItemClearCheck()
69        {
70            foreach (ToolStripMenuItem it in mdiForm.toolStripDropDownButton1.DropDownItems)
71            {
72                it.Checked = false;
73            }
74        }
75    }
76}