/// <summary>
		/// Replaces the current version with a new version.
		/// </summary>
		/// <param name="change">Change from current version to new version</param>
		public void AppendChange(TextChangeEventArgs change)
		{
			if (change == null)
				throw new ArgumentNullException("change");
			currentVersion.change = change;
			currentVersion.next = new Version(currentVersion);
			currentVersion = currentVersion.next;
		}
 protected virtual void OnTextChanged(TextChangeEventArgs e)
 {
     var handler = TextChanged;
     if (handler != null) handler(this, e);
 }