using System;
using System.Drawing;
using System.Windows.Forms;
using System.Runtime.InteropServices;

public enum HotkeyModifiers
{
    Alt = 1,
    Control = 2,
    Shift = 4,
    Win = 8
}

public class MyForm:Form
{
    [DllImport ("user32.dll")]
    private static extern bool RegisterHotKey (IntPtr hWnd, int id, int modifiers, Keys vk);

    [DllImport ("user32.dll")]
    private static extern bool UnregisterHotKey (IntPtr hWnd, int id);

    const int WM_HOTKEY = 0x312;
    const int WM_SYSCOMMAND = 0X112;
    const int SC_MAXMIZE = 0xf030;
    const int SC_MINMIZE = 0xf020;
    const int SC_CLOSE = 0xf060;

    public MyForm ()
    {
        NotifyIcon ni = new NotifyIcon (){ Icon = this.Icon, Visible = true };
        //RegisterHotKey
        bool bOK = RegisterHotKey (this.Handle, 0, (int)HotkeyModifiers.Win, Keys.F10);

        this.Closing += delegate {
            UnregisterHotKey (this.Handle, 0);
        };

        ni.MouseDown += (sender, e) => {
            if (e.Button == MouseButtons.Left) {
                this.Activate ();
                this.Visible = true;
            }
            if (e.Button == MouseButtons.Right) {
                if (DialogResult.Yes==MessageBox.Show("Quit? Realy?","Quit",MessageBoxButtons.YesNo)) {
                    this.Close ();
                }
            }
        };
    }

    //WndProc
    protected override void WndProc (ref Message m)
    {
        switch (m.Msg) {
        case WM_SYSCOMMAND:
            int code = m.WParam.ToInt32 ();
            if (code == SC_CLOSE || code == SC_MINMIZE) {
                this.Visible = false;
                return;//Must Prevent WndProc
            }
            break; //others, such as SC_MAXMIZE must in WndProc.
        case WM_HOTKEY:
            this.Text = DateTime.Now.ToString ();
            this.Activate ();
            this.Visible = true;
            break;
        }
        base.WndProc (ref m);
    }
}

public class MyClass
{
    public static void Main ()
    {
        MyForm form = new MyForm ();
        Application.Run (form);
    }
}