gistfile1.cs

namespace DFS
{
    using System;
    using System.Collections.Generic;
    using System.Linq;

    public class Control
    {
        public Control(string id)
        {
            Id = id;
        }

        public string Id { get; private set; }
        public Control[] Controls { get; set; }
    }

    public class MyControl : Control
    {
        public MyControl(string id)
            : base(id)
        {
        }
    }

    public static class ControlExtensions
    {       
        public static T FindFirstControlOfTypeBreadthFirst<T>(this Control rootControl) where T : Control
        {
            var fringe = new Queue<Control>();

            fringe.Enqueue(rootControl);

            while (fringe.Count > 0)
            {
                var current = fringe.Dequeue();
                Console.WriteLine("Visiting {0}", current.Id);

                var check = current as T;
                if (check != null)
                {
                    return check;
                }
                if (current.Controls != null)
                {
                    foreach (var child in current.Controls)
                    {
                        fringe.Enqueue(child);
                    }
                }
            }
            return null;
        }

        private class Program
        {
            private static void Main(string[] args)
            {
                var graph = new Control("root")
                {
                    Controls = new[]
                    {
                        new Control("1")
                        {
                            Controls = new[]
                            {
                                new Control(("11")) { Controls = new[] { new Control("111"), new MyControl("112") } },
                                new Control(("12")) { Controls = new[] { new Control("121"), new Control("122") } }
                            }
                        },
                        new Control("2")
                        {
                            Controls = new[]
                            {
                                new Control(("21")) { Controls = new[] { new Control("211"), new Control("212") } },
                                new Control(("22")) { Controls = new[] { new Control("221"), new Control("222") } }
                            }
                        },
                        new Control("3")
                        {
                            Controls = new[]
                            {
                                new Control(("31")) { Controls = new[] { new Control("311"), new Control("312") } },
                                new Control(("32")) { Controls = new[] { new Control("321"), new Control("322") } }
                            }
                        },
                        new Control("4")
                        {
                            Controls = new[]
                            {
                                new Control(("41")) { Controls = new[] { new Control("4111"), new Control("412") } },
                                new Control(("42")) { Controls = new[] { new Control("421"), new Control("422") } }
                            }
                        },
                    }
                };

                Console.WriteLine("Searching breadth-first");
                var match = graph.FindFirstControlOfTypeBreadthFirst<MyControl>();
                Console.WriteLine("Found control {0}", match.Id);   
            }
        }
    }

    // Output:
 
    //  Searching breadth-first
    //  Visiting root
    //  Visiting 1
    //  Visiting 2
    //  Visiting 3
    //  Visiting 4
    //  Visiting 11
    //  Visiting 12
    //  Visiting 21
    //  Visiting 22
    //  Visiting 31
    //  Visiting 32
    //  Visiting 41
    //  Visiting 42
    //  Visiting 111
    //  Visiting 112
    //  Found control 112
}