Enumerate browser tabs from external application

A bit of an odd (challenging?) question. Is it possible to programmatically access the tabs of an open browser from a external application? I realize that's a vague question, but hear me out:

What I'm trying to create is a "Gmail Chat Notifier" application that flashes a notification icon in the Windows system tray when an unanswered chat message exists. Right now, as far as I can tell, the only built-in Gmail chat notifications are:

Enable sounds (which I don't prefer)
Watch the window/tab/page title for the alternating flashing "Gmail" / "Blah says..." message.

The problem with #2 is: When the browser window is minimized, and when the Gmail tab isn't the active tab in the browser, the window title doesn't change and I don't notice new chat messages.

So I'd like to create an application that watches the tab titles for me. (All of the tab titles, not just the window title, which is only the active tab title.) I created a proof-of-concept C# application to detect unanswered chat messages by enumerating the active Windows processes and watching for the flashing "Blah says..." in the window title:

Process[] procs = Process.GetProcesses();
IntPtr hWnd;
foreach (Process proc in procs)
    if ((hWnd = proc.MainWindowHandle) != IntPtr.Zero)
        if (proc.MainWindowTitle.IndexOf(" says… ") >= 0)
        ...

But the obvious problem with this is that it won't work when the Gmail tab isn't the active/focused tab (since it only looks at window titles). So I need something that can dig deeper and look at the tab titles.

I'm open to anything. What I had been thinking might work is finding a way to enumerate the browser's tabs somehow (MDI child windows? * fingers crossed *), but maybe that's not even close to possible :) I'm also open to other solutions too if there's a way to do this with, say, Firefox plugins or something (but it'd be nice to integrate with the Windows system tray, and not just exist in the browser sandbox).

Can anyone help get me started? Thanks much in advance.

It's not possible in general. Browser tabs need not be MDI child windows (in fact, they almost certainly aren't). You do not know the window tree of an arbitrary browser, so you can't parse that and figure out the tabs (and even if you knew it for a specific browser, it's definitely an implementation detail that is likely to change even between minor releases). In fact, you do not know if the browser is even using separate Win32 window handles for tabs, as it may just have one handle for its main window, and draw everything inside by itself (e.g. Qt and WPF applications do that, and I believe that Opera in particular does that, and probably so does Safari).

Any solution to this will have to be browser-specific. You can probably write corresponding plugins for IE and Firefox to communicate that info to your application (though Firefox plugins are sandboxed, so I'm not sure if they are even able to do IPC). I don't see any options for Opera, Safari or Chrome.