Extender provider to simplify file/folder selection

using System;
using System.ComponentModel;
using System.Windows.Forms;
using System.Collections;
using System.Drawing;

namespace MavComponents
{
	/// <summary>
	/// FileBrowserExtenderProviderBase serves as base class for file browser extenders
	/// </summary>
	[ProvideProperty("BrowseButton", typeof(Control))]
	public abstract class FileBrowserExtenderProviderBase : Component, IExtenderProvider
	{
		private Hashtable extendees;
		protected FileDialog fileDialog;

		public FileBrowserExtenderProviderBase()
		{
			extendees = new Hashtable();
		}

		// Save the contents of the FileDialog
		[DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
		public System.Windows.Forms.FileDialog FileDialog
		{
			get {  return fileDialog; }
		}

		#region IExtenderProvider Member

		public bool CanExtend(object extendee)
		{
			return (extendee is Control);
		}

		[DefaultValue(null)]
		public Control GetBrowseButton(Control extendee)
		{
			if (extendees.Contains(extendee))
				return (Control)extendees[extendee];
			else
				return null;
		}

		public void SetBrowseButton(Control extendee, Control browseButton)
		{
			if (DesignMode && (extendee == browseButton))
			{
				string correctCode = "SetBrowseButton("+extendee.Name+", "+browseButton.Name+");";
				throw new ApplicationException("Because of a bug in the code generation you cannot set a control to be its own BrowseButton  in the visual designer.\r\nAdding the call to SetBrowseButton() to code does work, though.\r\n\r\nYou might consider adding this line to your code:\r\n"+correctCode);
			}

			if (extendees.Contains(extendee))
			{
				Control btn = extendees[extendee] as Control;
				btn.Click -= new EventHandler(browseButton_Click);
				extendees.Remove(extendee);
			}

			if (browseButton == null)
				return;

			extendees[extendee] = browseButton;
			browseButton.Click += new EventHandler(browseButton_Click);
		}
		#endregion

		private void browseButton_Click(object sender, EventArgs e)
		{
			Control btn = sender as Control;

			if (fileDialog.ShowDialog(btn.FindForm()) == DialogResult.OK)
			{
				// Find the accompanying target and set it's text
				foreach (DictionaryEntry ent in extendees)
				{
					if (ent.Value == btn)
					{
						Control target = ent.Key as Control;
						target.Text = fileDialog.FileName;
						return;
					}
				}
			}
		}
	}
}