How to tell a good chance to set the handler BHO?

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C#

browser

HI, all.
I am try to develop a BHO to add "super drag and go" into IE9. Now I meet some problems.
As we know, BHO will fail when the IE tab is refreshed or re-navigated. As "NavigateComplete2" never happen when refreshing, I have no good idea to differ “navigate” and “refresh”, I cannot find an exact chance to set the handler.
1. "BeforeNavigate2" never happens. It might be a bug in Windows 7??
2. "NavigateComplete2" and "DocumentComplete", with "pDisp == ieInstance". Do they indeed happen only one time? Although the page is very complicated?
3. A new IE tab opened by directly clicking a link, it cannot be set a handler?