Native C++ VS2010 Addin - Caret position screen coordinates

Hello,
I need to get screen coordinates of caret position within text editor in VS 2010.
Note, that is it not a .NET project (it is ATL), so it would be fine if it would work without need to create interop library.

Does anything accessible from native C++ Addin provide a way to get information I need?
 

Seems that WPF does not cooperate with Win32 API :(
I have tried following Win32 API calls without success:

HWND hwnd = ::GetForegroundWindow();
DWORD remoteThreadId = ::GetWindowThreadProcessId(hwnd, NULL);
DWORD currentThreadId = ::GetCurrentThreadId();
::AttachThreadInput(remoteThreadId, currentThreadId, TRUE);
HWND focused = ::GetFocus();
POINT pnt;
BOOL caret = ::GetCaretPos(&pnt) && ::ClientToScreen(focused, &pnt);
::AttachThreadInput(remoteThreadId, currentThreadId, FALSE);

and also:

HWND hwnd = ::GetForegroundWindow();
DWORD remoteThreadId = ::GetWindowThreadProcessId(hwnd, NULL);
GUITHREADINFO thr_info;thr_info.cbSize = sizeof(thr_info);
if (GetGUIThreadInfo(remoteThreadId, &thr_info))
{   
...
}

Thanks in advance.