public static bool ShowSelector(Form parent, string filename)
 {
     LoadUsersData(filename);
     using (var f = new FrmUserList())
     {
         f.Text = @"Вход в систему";
         return(f.ShowDialog(parent) != DialogResult.Cancel);
     }
 }
 public static void ShowEditor(Form parent, string filename)
 {
     LoadUsersData(filename);
     using (var f = new FrmUserList(true))
     {
         f.ShowDialog(parent);
     }
     SaveUsersData(filename);
 }