CVPCB window prefs don't save

[ocb-hd-ccb]

I organize different windows to different parts of my screen. Every time I open a kicad program it opens to where I last had it...EXCEPT for CVPCB. Several nightlies ago this was not an issue so something changed recently.

Macos Nightly 190916

```
Application: KiCad
Version: (5.99.0-132-g961fbf5f5), debug build
Libraries:
    wxWidgets 3.0.4
    libcurl/7.54.0 LibreSSL/2.6.5 zlib/1.2.11 nghttp2/1.24.1
Platform: Mac OS X (Darwin 18.7.0 x86_64), 64 bit, Little endian, wxMac
Build Info:
    wxWidgets: 3.0.4 (wchar_t,STL containers,compatible with 2.8)
    Boost: 1.69.0
    OpenCASCADE Community Edition: 6.9.1
    Curl: 7.54.0
    Compiler: Clang 9.0.0 with C++ ABI 1002

Build settings:
    KICAD_SCRIPTING=ON
    KICAD_SCRIPTING_MODULES=ON
    KICAD_SCRIPTING_PYTHON3=OFF
    KICAD_SCRIPTING_WXPYTHON=ON
    KICAD_SCRIPTING_WXPYTHON_PHOENIX=OFF
    KICAD_SCRIPTING_ACTION_MENU=ON
    BUILD_GITHUB_PLUGIN=ON
    KICAD_USE_OCE=ON
    KICAD_USE_OCC=OFF
    KICAD_SPICE=ON
    KICAD_STDLIB_DEBUG=OFF
    KICAD_STDLIB_LIGHT_DEBUG=OFF
    KICAD_SANITIZE=OFF
```

[KiCad Janitor (kicad-janitor)]

Fixed in revision 9ceca583b1edcba2198c0dbd1a07caf69d62f93e
https://git.launchpad.net/kicad/patch/?id=9ceca583b1edcba2198c0dbd1a07caf69d62f93e