The wrong way to validate and close a modal form

winforms_modal_form_bad.cs

public event EventHandler OkClick;  // Eliminate custom event

public bool Success { get; set; }  // Eliminate custom flag

private void btnOK_Click(object sender, EventArgs e)  
{
    if (Validate())
    {
        _selectedUsers.Clear();

        foreach (var user in _allUsers.Where(u => u.Selected))
            _selectedUsers.Add(user.UserId, user.UserName);

        if (OkClick != null)
            OkClick(this, new EventArgs());  // Custom event is unnecessary

        // Eliminate the custom flag by using the DialogResult property
        this.Success = true;

        // Unnecessary when the button's DialogResult property is set to OK.
        // Form will automatically close.
        this.Hide();
    }
}

// This method can be removed  
private void btnCancel_Click(object sender, EventArgs e)  
{
    // Eliminate the custom flag by using the DialogResult property.
    this.Success = false;

    // Unnecessary when the button's DialogResult property is set to Cancel.
    // Form will automatically close.
    this.Hide();
}