form1.cs
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace p272_18
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void newToolStripMenuItem_Click(object sender, EventArgs e)
{
Form2 newMDIChild = new Form2();
newMDIChild.MdiParent = this;
newMDIChild.Show();
num++;
//MessageBox.Show(sender.ToString());//显示的是new..
//this.editToolStripMenuItem = new System.Windows.Forms.ToolStripMenuItem();
if (num >= 1)
{
this.editToolStripMenuItem1.Visible = true;
}
}
public static int num = 0;
private void Form1_MdiChildActivate(object sender, EventArgs e)
{
if (num == 0)
{
this.editToolStripMenuItem1.Visible = false;
}
}
}
}
form2.cs
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace p272_18
{
public partial class Form2 : Form
{
public Form2()
{
InitializeComponent();
}
private void Form2_FormClosed(object sender, FormClosedEventArgs e)
{
Form1.num--;
}
}
}