Hi,
IE does not expose the internal workings of it's Tab Browsing infrastructure. Which is to say, there is no ITabWindowManager interface you can use. Switching tabs in IE involves a lot more than subclassing the windows. You have to switch out the ITBar, re-wire all the internal interfaces that connect the frame to the ITBar, update the TabBand UI (which, btw, isn't even written using GDI objects, so you can't do anything to it by subclassing it), etc. You can't do any of these things via external mechanisms.
check out this link
http://social.msdn.microsoft.com/Forums/en-US/ieextensiondevelopment/thread/b5ae318c-f177-4899-a5eb-de8c11a1ef19/
http://msdn.microsoft.com/en-us/ie/cc307217.aspx
Hope it will help you.