pa-0 / cs.self-dismissing-dialog

https://stackoverflow.com/a/78196439/5438626

Self-Closing Form

As I understand it, you want the form to self-close with DialogResult.OK. If the form is being shown modally (because ShowDialog was invoked on it) then you can set the dialog result directly and the form will close as a result. For example, when this form is shown by ShowDialog it will self-close after a 10-second countdown.

Self-Close

public partial class ConnPropsForm : Form
{
    public ConnPropsForm() => InitializeComponent();
    protected override void OnVisibleChanged(EventArgs e)
    {
        base.OnVisibleChanged(e);
        if(Visible)
        {
            _ = ExecAutoClose();
        }
    }
    private async Task ExecAutoClose()
    {
        int remaining = 10;
        do
        {
            label1.Text = $"Closing in {remaining:d2}";
            await Task.Delay(TimeSpan.FromSeconds(1));
            remaining--;
        } while(Visible && remaining > 0);
        DialogResult = DialogResult.OK;
    }
}

---

The calling method can do the same thing. Here, the main form aborts the countdown after 5 seconds the first time (only) that ConnPropsForm is shown.

External-Close

public partial class MainForm : Form
{
    public MainForm()
    {
        InitializeComponent();
        Disposed += (sender, e) =>ConnPropsForm.Dispose();
        buttonShow.Click += (sender, e) =>
        {
            if (!ConnPropsForm.Visible)
            {
                Text = ConnPropsForm.ShowDialog(this).ToString();
            }
        };
    }
    protected override async void OnLoad(EventArgs e)
    {
        base.OnLoad(e);
        BeginInvoke(() => Text = ConnPropsForm.ShowDialog(this).ToString());

        await Task.Delay(TimeSpan.FromSeconds(5));
        ConnPropsForm.DialogResult = DialogResult.Abort;
    }
    ConnPropsForm ConnPropsForm = new ConnPropsForm();
}