You need to control the opening of sub forms from a main form.
In my case I'm opening a Login window first before I launch my form1. I control everything from Program.cs. Set up a validation flag in Program.cs. Open Login window from Program.cs. Control then goes to login window. Then if the validation is good, set the validation flag to true from the login window. Now you can safely close the login window. Control returns to Program.cs. If the validation flag is true, open form1. If the validation flag is false, your application will close.
In Program.cs:
static class Program
{
/// <summary>
/// The main entry point for the application.
/// </summary>
///
//Validation flag
public static bool ValidLogin = false;
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Login());
if (ValidLogin)
{
Application.Run(new Form1());
}
}
}
In Login.cs:
private void btnOK_Click(object sender, EventArgs e)
{
if (txtUsername.Text == "x" && txtPassword.Text == "x")
{
Program.ValidLogin = true;
this.Close();
}
else
{
MessageBox.Show("Username or Password are incorrect.");
}
}
private void btnExit_Click(object sender, EventArgs e)
{
Application.Exit();
}