BrowserSelect.frm_settings.btn_apply_Click C# (CSharp) Method

        private void btn_apply_Click(object sender, EventArgs e)
        {
            //save rules

            //clear rules (instead of checking for changes we just overwrite the whole ruleset)
            Settings.Default.AutoBrowser.Clear();
            foreach (var rule in rules)
            {
                //check if rule has both pattern and browser defined
                if (rule.valid())
                    //add it to rule list
                    Settings.Default.AutoBrowser.Add(rule.ToString());
                else
                {
                    //ignore rule if both pattern and browser is empty otherwise inform user of missing part
                    var err = rule.error();
                    if (err.Length > 0)
                    {
                        MessageBox.Show("Invalid Rule: " + err);
                    }
                }

            }
            //save rules
            Settings.Default.Save();
            //Enabled property of apply button is used as a flag for unsaved changes
            btn_apply.Enabled = false;
            btn_cancel.Text = "Close";
        }