菜单条问题:为什么菜单条总是占用子窗口的区域？？？？实在时没分了，先欠着大家的。

1:菜单条问题:为什么菜单条总是占用子窗口的区域？

2：为了看到直接效果，此代码可直接编译：csc *.csc;然后运行


//CODE
class MdiChildFrame : System.Windows.Forms.Form
{
public MdiChildFrame() {
System.Windows.Forms.MenuStrip mainMenu = new System.Windows.Forms.MenuStrip();
System.Windows.Forms.ToolStripMenuItem[] subMenu = {new System.Windows.Forms.ToolStripMenuItem()};
System.Windows.Forms.ToolStripMenuItem[] openFileMenu = {new System.Windows.Forms.ToolStripMenuItem()};

mainMenu.Text = "子窗口_主菜单";
mainMenu.Items.AddRange(subMenu);
this.Controls.Add(mainMenu);
this.MainMenuStrip = mainMenu;

subMenu[0].Text = "子窗口_文件";
subMenu[0].DropDownItems.AddRange(openFileMenu);
mainMenu.AllowMerge = true;
openFileMenu[0].Text = "子窗口_打开";
}
protected override void OnPaint(System.Windows.Forms.PaintEventArgs e) 
 {
  System.Drawing.Pen pen = new System.Drawing.Pen(System.Drawing.Color.Red);
System.Drawing.Rectangle  rect = new System.Drawing.Rectangle(0,0,100,100);
e.Graphics.DrawRectangle(pen,rect);
 }
};

class MdiMainFrame : System.Windows.Forms.Form
{
public MdiMainFrame() {
this.IsMdiContainer = true;
MdiChildFrame childFrame = new MdiChildFrame();
childFrame.MdiParent = this;
//
System.Windows.Forms.MenuStrip mainMenu = new System.Windows.Forms.MenuStrip();
System.Windows.Forms.ToolStripMenuItem[] subMenu = {new System.Windows.Forms.ToolStripMenuItem()};
System.Windows.Forms.ToolStripMenuItem[] openFileMenu = {new System.Windows.Forms.ToolStripMenuItem()};

mainMenu.AllowMerge = true;
mainMenu.Text = "主菜单";
mainMenu.Items.AddRange(subMenu);
this.Controls.Add(mainMenu);
this.MainMenuStrip = mainMenu;

subMenu[0].Text = "文件";
subMenu[0].DropDownItems.AddRange(openFileMenu);

openFileMenu[0].Text = "打开";



//
this.Show();
childFrame.Show() ;
}

public static void Main(string[] args)
{

System.Windows.Forms.Application.Run(new MdiMainFrame());
}
};

补充：.NET技术 ,  C#