Prevent that AxAcroPDF steals focus when it loads a new file

AxAcroPDFFocusExtensions.cs

 /// <summary>
   /// Extensions for the Acrobat ActiveX control
   /// /* Copyright (c) 2014 Bert Van Steen */
   /// <example>
   ///    axAcroPDF1.SuspendStealFocus(TimeSpan.FromMilliseconds(300));
   ///    axAcroPDF1.LoadFile(scanFilename);
   /// </example>
   /// </summary>
   static class AxAcroPDFFocusExtensions
   {
      struct TimerTag
      {
         public TimerTag(AxAcroPDF control, object controlTag)
         {
            Control = control;
            ControlTag = controlTag;
         }

         public object ControlTag;
         public AxAcroPDF Control;
      }

      /// <summary>
      /// Prevent Adobe AxAcroPDF from stealing focus when you change the src. 
      /// The control will be disabled for 250 ms
      /// /// <param name="pdfControl">The acrobat ActiveX control</param>
      /// </summary>
      public static void SuspendStealFocus(this AxAcroPDF pdfControl)
      {
         SuspendStealFocus(pdfControl, 250);
      }

      /// <summary>
      /// Prevent Adobe AxAcroPDF from stealing focus when you change the src. 
      /// </summary>
      /// <param name="pdfControl">The acrobat ActiveX control</param>
      /// <param name="timeSpan">Time the ActiveX will be inaccessible (and not grabbing focus)</param>
      public static void SuspendStealFocus(this AxAcroPDF pdfControl, TimeSpan timeSpan)
      {
         SuspendStealFocus(pdfControl, (int)timeSpan.TotalMilliseconds);
      }

      /// <summary>
      /// Prevent Adobe AxAcroPDF from stealing focus when you change the src. 
      /// </summary>
      /// <param name="pdfControl">The acrobat ActiveX control</param>
      //// <param name="timeoutInMilliSeconds">Number of milliseconds the ActiveX will be inaccessible (and not grabbing focus)</param>
      public static void SuspendStealFocus(this AxAcroPDF pdfControl, int timeoutInMilliSeconds)
      {
         pdfControl.Enabled = false;
       
         Timer t = new Timer();
         t.Interval = timeoutInMilliSeconds;
         t.Tick += t_Tick;
         t.Start();

         pdfControl.Tag = Guid.NewGuid();
         t.Tag = new TimerTag(pdfControl, pdfControl.Tag);
      }
      
      static void t_Tick(object sender, EventArgs e)
      {
         var timer = (Timer)sender;
         timer.Stop();
         timer.Dispose();

         TimerTag t = (TimerTag) timer.Tag;
         if (ReferenceEquals(t.Control.Tag, t.ControlTag))
         {
            t.Control.Enabled = true;
         }
      }