Single Form Hide on Startup

I'm coming at this from C#, but should be very similar in vb.net.

In your main program file, in the Main method, you will have something like:

Application.Run(new MainForm());

This creates a new main form and limits the lifetime of the application to the lifetime of the main form.

However, if you remove the parameter to Application.Run(), then the application will be started with no form shown and you will be free to show and hide forms as much as you like.

Rather than hiding the form in the Load method, initialize the form before calling Application.Run(). I'm assuming the form will have a NotifyIcon on it to display an icon in the task bar - this can be displayed even if the form itself is not yet visible. Calling Form.Show() or Form.Hide() from handlers of NotifyIcon events will show and hide the form respectively.

I use this:

private void MainForm_Load(object sender, EventArgs e)
{
    if (Settings.Instance.HideAtStartup)
    {
        BeginInvoke(new MethodInvoker(delegate
        {
            Hide();
        }));
    }
}

Obviously you have to change the if condition with yours.

Extend your main form with this one:

using System.Windows.Forms;

namespace HideWindows
{
    public class HideForm : Form
    {
        public HideForm()
        {
            Opacity = 0;
            ShowInTaskbar = false;
        }

        public new void Show()
        {
            Opacity = 100;
            ShowInTaskbar = true;

            Show(this);
        }
    }
}

For example:

namespace HideWindows
{
    public partial class Form1 : HideForm
    {
        public Form1()
        {
            InitializeComponent();
        }
    }
}

More info in this article (spanish):

http://codelogik.net/2008/12/30/primer-form-oculto/

Put this in your Program.cs:

FormName FormName = new FormName ();

FormName.ShowInTaskbar = false;
FormName.Opacity = 0;
FormName.Show();
FormName.Hide();

Use this when you want to display the form:

var principalForm = Application.OpenForms.OfType<FormName>().Single();
principalForm.ShowInTaskbar = true;
principalForm.Opacity = 100;
principalForm.Show();

Launching an app without a form means you're going to have to manage the application startup/shutdown yourself.

Starting the form off invisible is a better option.

This example supports total invisibility as well as only NotifyIcon in the System tray and no clicks and much more.

More here: http://code.msdn.microsoft.com/TheNotifyIconExample

static void Main()
{
    Application.EnableVisualStyles();
    Application.SetCompatibleTextRenderingDefault(false);
    MainUIForm mainUiForm = new MainUIForm();
    mainUiForm.Visible = false;
    Application.Run();
}

I had an issue similar to the poster's where the code to hide the form in the form_Load event was firing before the form was completely done loading, making the Hide() method fail (not crashing, just wasn't working as expected).

The other answers are great and work but I've found that in general, the form_Load event often has such issues and what you want to put in there can easily go in the constructor or the form_Shown event.

Anyways, when I moved that same code that checks some things then hides the form when its not needed (a login form when single sign on fails), its worked as expected.

    static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Form1 form1 = new Form1();
            form1.Visible = false;
            Application.Run();

        }
 private void ExitToolStripMenuItem_Click(object sender, EventArgs e)
        {
            this.Close();
            Application.Exit();
        }

Here is a simple approach:
It's in C# (I don't have VB compiler at the moment)

public Form1()
{
    InitializeComponent();
    Hide(); // Also Visible = false can be used
}

private void Form1_Load(object sender, EventArgs e)
{
    Thread.Sleep(10000);
    Show(); // Or visible = true;
}

In the designer, set the form's Visible property to false. Then avoid calling Show() until you need it.

A better paradigm is to not create an instance of the form until you need it.

Based on various suggestions, all I had to do was this:

To hide the form:

Me.Opacity = 0
Me.ShowInTaskbar = false

To show the form:

Me.Opacity = 100
Me.ShowInTaskbar = true

Why do it like that at all?

Why not just start like a console app and show the form when necessary? There's nothing but a few references separating a console app from a forms app.

No need in being greedy and taking the memory needed for the form when you may not even need it.