private void BtAddItem_Click(object sender, EventArgs e) { var url = ""; if (FormUtils.InputBox("Add new website", "Enter a website Url to check ", ref url) != DialogResult.OK) { return; } if (!ValidationUtils.IsUrlValid(url)) { MessageBox.Show($"{url} is not a valid Url"); return; } cklbDrives.Items.Add(url); }