Just set the form to Topmost with no border style, then set maximized.
Note: This must be done in the order below or it will not work correctly.
protected override void OnLoad(EventArgs e)
{
base.OnLoad(e);
this.TopMost = true;
this.FormBorderStyle = FormBorderStyle.None;
this.WindowState = FormWindowState.Maximized;
}
Alternatively you can hook to the event rather than overriding.
private void Form1_Load(object sender, EventArgs e)
{
this.TopMost = true;
this.FormBorderStyle = FormBorderStyle.None;
this.WindowState = FormWindowState.Maximized;
}