Show a Balloon notification

Question

You have not actually specified an icon to display in the task bar. Running your code in LINQPad, by simply adding notifyIcon.Icon = SystemIcons.Application before the call to ShowBalloonTip I was able to get the tip to be displayed. Also note that you should call Dispose when you are done with your NotifyIcon instance.

Matthew identified the issue, but I still struggled to put all the pieces together. So I thought a concise example that works in LINQPad as-is would be helpful (and presumably elsewhere). Just reference the System.Windows.Forms assembly, and paste this code in.

var notification = new System.Windows.Forms.NotifyIcon()
{
    Visible = true,
    Icon = System.Drawing.SystemIcons.Information,
    // optional - BalloonTipIcon = System.Windows.Forms.ToolTipIcon.Info,
    // optional - BalloonTipTitle = "My Title",
    BalloonTipText = "My long description...",
};

// Display for 5 seconds.
notification.ShowBalloonTip(5000);

// This will let the balloon close after it's 5 second timeout
// for demonstration purposes. Comment this out to see what happens
// when dispose is called while a balloon is still visible.
Thread.Sleep(10000);

// The notification should be disposed when you don't need it anymore,
// but doing so will immediately close the balloon if it's visible.
notification.Dispose();

See the below source code.

using System;
using System.ComponentModel;
using System.Drawing;
using System.IO;
using System.Reflection;
using System.Windows.Forms;

namespace ShowToolTip
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btBallonToolTip_Click(object sender, EventArgs e)
        {
            ShowBalloonTip();
            this.Hide();
        }

        private void ShowBalloonTip()
        {
            Container bpcomponents = new Container();
            ContextMenu contextMenu1 = new ContextMenu();

            MenuItem runMenu = new MenuItem();
            runMenu.Index = 1;
            runMenu.Text = "Run...";
            runMenu.Click += new EventHandler(runMenu_Click);

            MenuItem breakMenu = new MenuItem();
            breakMenu.Index = 2;
            breakMenu.Text = "-------------";

            MenuItem exitMenu = new MenuItem();
            exitMenu.Index = 3;
            exitMenu.Text = "E&xit";

            exitMenu.Click += new EventHandler(exitMenu_Click);

            // Initialize contextMenu1
            contextMenu1.MenuItems.AddRange(
                        new System.Windows.Forms.MenuItem[] { runMenu, breakMenu, exitMenu });

            // Initialize menuItem1

            this.ClientSize = new System.Drawing.Size(0, 0);
            this.Text = "Ballon Tootip Example";

            // Create the NotifyIcon.
            NotifyIcon notifyIcon = new NotifyIcon(bpcomponents);

            // The Icon property sets the icon that will appear
            // in the systray for this application.
            string iconPath = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location) + @"\setup-icon.ico";
            notifyIcon.Icon = new Icon(iconPath);

            // The ContextMenu property sets the menu that will
            // appear when the systray icon is right clicked.
            notifyIcon.ContextMenu = contextMenu1;

            notifyIcon.Visible = true;

            // The Text property sets the text that will be displayed,
            // in a tooltip, when the mouse hovers over the systray icon.
            notifyIcon.Text = "Morgan Tech Space BallonTip Running...";
            notifyIcon.BalloonTipText = "Morgan Tech Space BallonTip Running...";
            notifyIcon.BalloonTipTitle = "Morgan Tech Space";
            notifyIcon.ShowBalloonTip(1000);
        }

        void exitMenu_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        void runMenu_Click(object sender, EventArgs e)
        {
            MessageBox.Show("BallonTip is Running....");
        }
    }
}

ShowBalloonnTip takes the number of milliseconds. 3 milliseconds might be too fast for you to even see. Try something more like 3000

You might need to pass a component model to the contructor. It's what I see in all the examples. Sorry been a long time since I've used it. See first answer here:

NotifyIcon not showing

For the sake of future coders:

the [timeout] parameter is deprecated as of windows vista

See: C# NotifyIcon Show Balloon Parameter Deprecated

So you might as well just put 0 into the parameter for > Windows Vista. What's worse, comments on the linked answer suggests that the replacement for these balloons, toast notifications, were only introduced in Windows 8. So for poor old Windows 7 falling between two stools, with Vista < 7 < 8, we seem to be at the mercy of however long Windows wants to keep that balloon there! It does eventually fade away, I've noticed, but after some empirical testing I'm quite sure that parameter is indeed being ignored.

So, building on the answers above, and in particular taking the lambda functions suggested by @jlmt in the comments, here's a solution that works for me on Windows 7:

//Todo: use abstract factory pattern to detect Windows 8 and in that case use a toastnotification instead
        private void DisplayNotificationBalloon(string header, string message)
        {
            NotifyIcon notifyIcon = new NotifyIcon
            {
                Visible = true,
                Icon = SystemIcons.Application
            };
            if (header != null)
            {
                notifyIcon.BalloonTipTitle = header;
            }
            if (message != null)
            {
                notifyIcon.BalloonTipText = message;
            }
            notifyIcon.BalloonTipClosed += (sender, args) => dispose(notifyIcon);
            notifyIcon.BalloonTipClicked += (sender, args) => dispose(notifyIcon);
            notifyIcon.ShowBalloonTip(0);
        }

        private void dispose(NotifyIcon notifyIcon)
        {
            notifyIcon.Dispose();
        }

Notes

• I've put a TODO in there to write another implementation for Windows 8, as people are 50/50 now on Windows 7/8 so would be good to support a newer functionality. I guess anyone else coding this for multiple versions of windows should probably do the same, ideally. Or just stop supporting 7 and switch to using ToastNotification.
• I purposely defined the disposal in a function so I could debug and verify that the breakpoint was indeed being hit.