/// <summary>
 /// An event handler called when a tool was removed from the toolbox.
 /// </summary>
 /// <param name="sender">The sender object.</param>
 /// <param name="e">The event arguments.</param>
 private void OnToolRemoved(object sender, ToolEventArgs e)
 {
     this.OnRemoveTool(e.Tool);
 }
 /// <summary>
 /// An event handler called when a tool was added to the toolbox.
 /// </summary>
 /// <param name="sender">The sender object.</param>
 /// <param name="e">The event arguments.</param>
 private void OnToolAdded(object sender, ToolEventArgs e)
 {
     this.OnAddTool(e.Tool);
 }