allow changing the page from keyboard in property sheet like controls even when the notebook doesn't have focus

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@40355 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/toplevel.h

@@ -103,6 +103,9 @@ public:
     // choose the right parent to use with CreateWindow()
     virtual WXHWND MSWGetParent() const;
 
+    // return true if the message was preprocessed and shouldn't be dispatched
+    virtual bool MSWProcessMessage(WXMSG* pMsg);
+
     // window proc for the frames
     WXLRESULT MSWWindowProc(WXUINT message, WXWPARAM wParam, WXLPARAM lParam);