Display both forms together

Question

I have 2 forms Form1 and Form2, when program executes I want both forms to display but Form2 with ShowDialog(); i.e user has to respond to Form2 before using Form1. How can I achieve this?

Form2 will take userinput and will display on Form1, so do I have to hide Form2 after user responds to Form2 or just kill it.

Answer 1

If you use ShowDialog, Form2 will automatically be hidden when hits OK or Cancel (assuming you've set the DialogResult property for any relevant buttons) but you will still need to dispose of it. You can do something like this:

using (Form f2 = new Form2())
{
    // Populate it with existing data
    DialogResult result = f2.ShowDialog();
    // Use the result and any data within f2
}

Answer 2

I would do this in a form like this:

public FormMain()
{
    InitializeComponent();
    //Visible should be set within InitializeComponent (or Designer)
    Visible = false;

    //Can't be done in constructor, or this.Close()
    //would lead to an exception.
    this.Load += (sender, e) =>
    {
        bool loginSuccessfull = false;

        using (var loginScreen = new FormLogin())
        {
            if (DialogResult.OK == loginScreen.ShowDialog())
            {
                //Maybe some other public function from loginScreen
                //is needed to determine if the login was successfull
                //loginSuccessfull = loginScreen.CheckCredentials();
                loginSuccessfull = true;
            }
        }

        if (loginSuccessfull)
        {
            Visible = true;
        }
        else
        {
            this.Close();
        }
    };
}