Added Stefan's fix for messages being incorrectly ignored.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_2_BRANCH@7174 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/os2/window.cpp

@@ -1813,7 +1813,7 @@ MRESULT EXPENTRY wxWndProc(
     {
         if (pWnd)
             rc = pWnd->OS2WindowProc(ulMsg, wParam, lParam);
-        else
+        if(!rc)
             rc = ::WinDefWindowProc(hWnd, ulMsg, wParam, lParam);
     }
     return rc;