How to attach mouse event listeners to embedded nsIWebBrowser in C++ - xpcom

Question

I've embedded an nsIWebBrowser in my application. Because I'm just generating HTML for it on the fly, I'm using OpenStream, AppendToStream, and CloseStream to add content. What I need is to add event listeners for mouse movement over the web browser as well as mouse clicks. I've read documentation and tried lots of different things, but nothing I have tried has worked. For instance, the code below would seem to do the right thing, but it does nothing:
nsCOMPtr<nsIDOMWindow> domWindow;
mWebBrowser->GetContentDOMWindow(getter_AddRefs(domWindow));
if (!mEventTarget) {
mEventTarget = do_QueryInterface(domWindow);
if (mEventTarget)
mEventTarget->AddEventListener(NS_LITERAL_STRING("mouseover"), (nsIDOMEventListener *)mEventListener, PR_FALSE);
}
Perhaps it isn't working because this is run during initialization, but before any content is actually added. However, if I add it during AppendStream, or CloseStream, it segfaults.
Please tell me a straightforward way to do this.

Answer 1

Well, here's the answer:
nsCOMPtr<nsIDOMEventTarget> cpEventTarget;
nsCOMPtr<nsIDOMWindow> cpDomWin;
m_pWebBrowser->GetContentDOMWindow (getter_AddRefs(cpDomWin));
nsCOMPtr<nsIDOMWindow2> cpDomWin2 (do_QueryInterface (cpDomWin));
cpDomWin2->GetWindowRoot(getter_AddRefs(cpEventTarget));
rv = cpEventTarget->AddEventListener(NS_LITERAL_STRING("mousedown"),
m_pBrowserImpl, PR_FALSE);