如何关闭表格?

我有这个代码显示/打开一个新的窗体:

在gkh_Keydown事件中，当我点击Ctrl + M时，它显示/打开新窗体。现在我想这样做，当我再次点击Ctrl + M，它将关闭新的窗体。

当我点击一次打开新表单时，它会先进入这个表单:

public MagnifierMainForm(bool showMain)
        {
            InitializeComponent();
            if (showMain == true)
            {
                GetConfiguration();
                //--- My Init ---
                FormBorderStyle = FormBorderStyle.None;
                TopMost = true;
                StartPosition = FormStartPosition.CenterScreen;
                mImageMagnifierMainControlPanel = Properties.Resources.magControlPanel20061222;
                if (mImageMagnifierMainControlPanel == null)
                    throw new Exception("Resource cannot be found!");
                Width = mImageMagnifierMainControlPanel.Width;
                Height = mImageMagnifierMainControlPanel.Height;
                HotSpot hsConfiguration = new HotSpot(new Rectangle(50, 15, 35, 30));
                hsConfiguration.OnMouseDown += new HotSpot.MouseEventDelegate(hsConfiguration_OnMouseDown);
                hsConfiguration.OnMouseUp += new HotSpot.MouseEventDelegate(hsConfiguration_OnMouseUp);
                hsConfiguration.OnMouseMove += new HotSpot.MouseEventDelegate(hsConfiguration_OnMouseMove);
                HotSpot hsMagnfier = new HotSpot(new Rectangle(10, 15, 30, 30));
                hsMagnfier.OnMouseMove += new HotSpot.MouseEventDelegate(hsMagnfier_OnMouseMove);
                hsMagnfier.OnMouseDown += new HotSpot.MouseEventDelegate(hsMagnfier_OnMouseDown);
                hsMagnfier.OnMouseUp += new HotSpot.MouseEventDelegate(hsMagnfier_OnMouseUp);
                HotSpot hsExit = new HotSpot(new Rectangle(95, 20, 15, 15));
                hsExit.OnMouseUp += new HotSpot.MouseEventDelegate(hsExit_OnMouseUp);
                mHotSpots.Add(hsConfiguration);
                mHotSpots.Add(hsMagnfier);
                mHotSpots.Add(hsExit);
                ShowInTaskbar = false;
                this.Show();
            }
            else
            {
                GetConfiguration();
                int x = mLastCursorPosition.X;
                int y = mLastCursorPosition.Y;
                MagnifierForm magnifier = new MagnifierForm(mConfiguration, System.Windows.Forms.Cursor.Position);//mLastCursorPosition);                
                magnifier.Show();
            }
        }

因为我设置了false，所以它在执行else部分:

GetConfiguration();
                    int x = mLastCursorPosition.X;
                    int y = mLastCursorPosition.Y;
                    MagnifierForm magnifier = new MagnifierForm(mConfiguration, System.Windows.Forms.Cursor.Position);//mLastCursorPosition);                
                    magnifier.Show();

magnifier.Show ();show new Form .

现在我想，如果我再次按Ctrl + M，它将关闭窗体放大镜。

所以在Form的gkh_KeyDown事件中在else部分我做了:

magnifierform.Close();

为magnifierform添加了一个新变量，并尝试关闭它。在magnifierform中，我输入:

public MagnifierForm(Configuration configuration, Point startPoint)
        {
            InitializeComponent();
            //--- My Init ---
            mConfiguration = configuration;
            FormBorderStyle = FormBorderStyle.None;
            ShowInTaskbar = mConfiguration.ShowInTaskbar;
            TopMost = mConfiguration.TopMostWindow;
            Width = mConfiguration.MagnifierWidth;
            Height = mConfiguration.MagnifierHeight;
            // Make the window (the form) circular
            GraphicsPath gp = new GraphicsPath();
            gp.AddEllipse(ClientRectangle);
            Region = new Region(gp);
            mImageMagnifier = Properties.Resources.magnifierGlass;
            mTimer = new Timer();
            mTimer.Enabled = true;
            mTimer.Interval = 20;
            mTimer.Tick += new EventHandler(HandleTimer);
            mScreenImage = new Bitmap(Screen.PrimaryScreen.Bounds.Width,
                                     Screen.PrimaryScreen.Bounds.Height);
            mStartPoint = startPoint;
            mTargetPoint = startPoint;
            if (mConfiguration.ShowInTaskbar)
                ShowInTaskbar = true;
            else
                ShowInTaskbar = false;
        }
        public MagnifierForm()
        {
        }

添加了一个不做任何事情的实例，因为我只想关闭它。但它从未关闭。

magnifierform是magnifierform的一个变量，我想直接关闭它，而不是像以前那样使用其他的MagnifierMainForm。

我只是想关闭它，但它从来没有关闭。我使用了一个断点:

magnifierform.Close();

在第二个Ctrl + M它到达那里，但它没有关闭MagnifierForm。什么也不做。

编辑

在MagnifierForm中添加了:

public MagnifierForm()
        {
            this.Close();
        }

在Form1中，在gkh_KeyDown事件中，我将其更改为:

else
                {
                    magnifierform = new MagnifierForm();
                }

所以我在第二个Ctrl + M上做断点在这里停止了但是当我继续时它并没有关闭表单

        Form frmToClose = null;
        foreach (Form frm in Application.OpenForms)
        {
            if (frm is MagnifierMainForm)
            {
                frmToClose = frm;
                break;
            }
        }
        if (frmToClose != null)
        {
            frmToClose.Close();
        }
        else
        {
            // create a new instance of MagnifierMainForm() and display it
        }