The run order about loaded event and onapplytemplate in custom control of Silverlight 2 beta 2

I 've created a customer control menulink. CS in Silverlight 2beta2, and the code like this:

1. Public class menulink: Control
2. {
3. Public menulink ()
4. {
5. Defaultstylekey = typeof (menulink );
6. This. Loaded + = new routedeventhandler (menulink_loaded );
7. }
9. Void menulink_loaded (Object sender, routedeventargs E)
10. {
12. }
14. Public override void onapplytemplate ()
15. {
16. Base. onapplytemplate ();
17. }
18. }

There is a canvas named 'menu 'in page 'page. XAML', and I add the menulink into the canvas dynamicly:

1. Public page ()
2. {
3. Initializecomponent ();
4. This. Loaded + = new routedeventhandler (page_loaded );
5. }
7. Void page_loaded (Object sender, routedeventargs E)
8. {
9. Menulink ML = new menulink (true );
10. Canmenu. Children. Clear ();
11. Canmenu. Children. Add (ML );
12. }

In this situation, the event in menulink. CS are called by this orders:

1. 1. Public menulink (bool)
2. 2. Void menulink_loaded (Object sender, routedeventargs E)
3. 3. Public override void onapplytemplate ()

But if I add the menulink after downloading a XML file in page. CS like this:

1. Public page ()
2. {
3. Initializecomponent ();
4. This. Loaded + = new routedeventhandler (page_loaded );
5. }
7. Void page_loaded (Object sender, routedeventargs E)
8. {
9. WebClient = new WebClient ();
10. WebClient. downloadstringcompleted + = new downloadstringcompletedeventhandler (webclient_downloadstringcompleted );
11. WebClient. downloadstringasync (New uri ("A. xml", urikind. Relative ));
12. }
14. Void webclient_downloadstringcompleted (Object sender, downloadstringcompletedeventargs E)
15. {
16. Menulink ML = new menulink (true );
17. Canmenu. Children. Clear ();
18. Canmenu. Children. Add (ML );
19. }

Then the order of events/methods called in menulink. CS like this:

1. 1. Public menulink (bool)
2. 2. Public override void onapplytemplate ()
3. 3. Void menulink_loaded (Object sender, routedeventargs E)

 

I really don't know why ?????