+// VZ: normally, the trick with subclassing the tooltip control and processing
+// TTM_WINDOWFROMPOINT should work but, somehow, it doesn't. I leave the
+// code here for now (but it's not compiled) in case we need it later.
+//
+// For now, instead of this, we just add all radiobox buttons to the
+// tooltip control as well (see SetWindow) - this is probably less
+// efficient, but it works.
+#define wxUSE_TTM_WINDOWFROMPOINT 1
+
+// ----------------------------------------------------------------------------
+// global variables
+// ----------------------------------------------------------------------------
+
+// the tooltip parent window
+WXHWND wxToolTip::ms_hwndTT = (WXHWND)NULL;
+
+#if wxUSE_TTM_WINDOWFROMPOINT
+
+// the tooltip window proc
+static WNDPROC gs_wndprocToolTip = (WNDPROC)NULL;
+
+#endif // wxUSE_TTM_WINDOWFROMPOINT