Control for tags with auto-completion in Winforms?

I am seeking a WinForm control that would provide an autocomplete behavior for multiple space-separated - exactly ala del.icio.us (or stackoverflow.com for that matter).

Does anyone knows how to do that within a .NET 2.0 WinForm application?

From stackoverflow Joannes Vermorel

• ComboBox can autocomplete, but only one word at a time.

  If you want to have each word separately autocompleted, you have to write your own.

  I already did, hope it's not too long. It's not 100% exactly what you want, this was used for autocompleting in email client when typing in email adress.

  /// <summary>
  /// Extended TextBox with smart auto-completion
  /// </summary>
  public class TextBoxAC: TextBox
  {
      private List<string> completions = new List<string>();
      private List<string> completionsLow = new List<string>();
      private bool autocompleting = false;
      private bool acDisabled = true;
  
      private List<string> possibleCompletions = new List<string>();
      private int currentCompletion = 0;
  
      /// <summary>
      /// Default constructor
      /// </summary>
      public TextBoxAC()
      {
          this.TextChanged += new EventHandler(TextBoxAC_TextChanged);
          this.KeyPress += new KeyPressEventHandler(TextBoxAC_KeyPress);
          this.KeyDown += new KeyEventHandler(TextBoxAC_KeyDown);
  
          this.TabStop = true;
      }
  
      /// <summary>
      /// Sets autocompletion data, list of possible strings
      /// </summary>
      /// <param name="words">Completion words</param>
      /// <param name="wordsLow">Completion words in lowerCase</param>
      public void SetAutoCompletion(List<string> words, List<string> wordsLow)
      {
          if (words == null || words.Count < 1) { return; }
  
          this.completions = words;
          this.completionsLow = wordsLow;
  
          this.TabStop = false;
      }
  
      private void TextBoxAC_TextChanged(object sender, EventArgs e)
      {
          if (this.autocompleting || this.acDisabled) { return; }
  
  
          string text = this.Text;
          if (text.Length != this.SelectionStart) { return; }
  
          int pos = this.SelectionStart;
          string userPrefix = text.Substring(0, pos);
          int commaPos = userPrefix.LastIndexOf(",");
  
          if (commaPos == -1)
          {
              userPrefix = userPrefix.ToLower();
              this.possibleCompletions.Clear();
              int n = 0;
              foreach (string s in this.completionsLow)
              {
                  if (s.StartsWith(userPrefix))
                  {
                      this.possibleCompletions.Add(this.completions[n]);
                  }
                  n++;
              }
              if (this.possibleCompletions.Count < 1) { return; }
  
              this.autocompleting = true;
              this.Text = this.possibleCompletions[0];
              this.autocompleting = false;
              this.SelectionStart = pos;
              this.SelectionLength = this.Text.Length - pos;
          }
          else
          {
              string curUs = userPrefix.Substring(commaPos + 1);
  
              if (curUs.Trim().Length < 1) { return; }
  
              string trimmed;
              curUs = this.trimOut(curUs, out trimmed);
              curUs = curUs.ToLower();
  
              string oldUs = userPrefix.Substring(0, commaPos + 1);
  
              this.possibleCompletions.Clear();
              int n = 0;
              foreach (string s in this.completionsLow)
              {
                  if (s.StartsWith(curUs))
                  {
                      this.possibleCompletions.Add(this.completions[n]);
                  }
                  n++;
              }
              if (this.possibleCompletions.Count < 1) { return; }
  
              this.autocompleting = true;
              this.Text = oldUs + trimmed + this.possibleCompletions[0];
              this.autocompleting = false;
              this.SelectionStart = pos;
              this.SelectionLength = this.Text.Length - pos + trimmed.Length;
          }
          this.currentCompletion = 0;
      }
  
      private void TextBoxAC_KeyDown(object sender, KeyEventArgs e)
      {
          if (e.KeyCode == Keys.Back || e.KeyCode == Keys.Delete)
          {
              this.acDisabled = true;
          }
  
          if (e.KeyCode == Keys.Up || e.KeyCode == Keys.Down)
          {
              if ((this.acDisabled) || (this.possibleCompletions.Count < 1))
              {
                  return;
              }
  
              e.Handled = true;
              if (this.possibleCompletions.Count < 2) { return; }
  
              switch (e.KeyCode)
              {
                  case Keys.Up:
                      this.currentCompletion--;
                      if (this.currentCompletion < 0)
                      {
                          this.currentCompletion = this.possibleCompletions.Count - 1;
                      }
                      break;
                  case Keys.Down:
                      this.currentCompletion++;
  
                      if (this.currentCompletion >= this.possibleCompletions.Count)
                      {
                          this.currentCompletion = 0;
                      }
                      break;
              }
  
              int pos = this.SelectionStart;
              string userPrefix = this.Text.Substring(0, pos);
              int commaPos = userPrefix.LastIndexOf(",");
  
              if (commaPos == -1)
              {
                  pos--;
                  userPrefix = this.Text.Substring(0, pos);
  
                  this.autocompleting = true;
                  this.Text = userPrefix + this.possibleCompletions[this.currentCompletion].Substring(userPrefix.Length);
                  this.autocompleting = false;
                  this.SelectionStart = pos + 1;
                  this.SelectionLength = this.Text.Length - pos;
              }
              else
              {
                  string curUs = userPrefix.Substring(commaPos + 1);
  
                  if (curUs.Trim().Length < 1) { return; }
  
                  string trimmed;
                  curUs = this.trimOut(curUs, out trimmed);
                  curUs = curUs.ToLower();
  
                  string oldUs = userPrefix.Substring(0, commaPos + 1);
  
                  this.autocompleting = true;
                  this.Text = oldUs + trimmed + this.possibleCompletions[this.currentCompletion];
                  this.autocompleting = false;
                  this.SelectionStart = pos;
                  this.SelectionLength = this.Text.Length - pos + trimmed.Length;
              }
          }
      }
  
      private void TextBoxAC_KeyPress(object sender, KeyPressEventArgs e)
      {
          if (!Char.IsControl(e.KeyChar)) { this.acDisabled = false; }
      }
  
      private string trimOut(string toTrim, out string trim)
      {
          string ret = toTrim.TrimStart();
  
          int pos = toTrim.IndexOf(ret);
          trim = toTrim.Substring(0, pos);
  
          return ret;
      }
  }
  

  From Jakub Kotrla