This is pretty simple. You just need to set window in off-screen area and animate it's position until it is fully visible. Here is a sample code:
public partial class Form1 : Form
{
private Timer timer;
private int startPosX;
private int startPosY;
public Form1()
{
InitializeComponent();
// We want our window to be the top most
TopMost = true;
// Pop doesn't need to be shown in task bar
ShowInTaskbar = false;
// Create and run timer for animation
timer = new Timer();
timer.Interval = 50;
timer.Tick += timer_Tick;
}
protected override void OnLoad(EventArgs e)
{
// Move window out of screen
startPosX = Screen.PrimaryScreen.WorkingArea.Width - Width;
startPosY = Screen.PrimaryScreen.WorkingArea.Height;
SetDesktopLocation(startPosX, startPosY);
base.OnLoad(e);
// Begin animation
timer.Start();
}
void timer_Tick(object sender, EventArgs e)
{
//Lift window by 5 pixels
startPosY -= 5;
//If window is fully visible stop the timer
if (startPosY < Screen.PrimaryScreen.WorkingArea.Height - Height)
timer.Stop();
else
SetDesktopLocation(startPosX, startPosY);
}
}