Reset all colors to default doesn't work

Description

When trying to reset all the colors to their default in the preferences panels, the colors are not reset properly to their default.

Before:

After:

Steps to reproduce

1. Open the preferences window of eeschema/pcbnew (it might also be broken in modedit, but I haven't tested it)
2. Navigate to the colors page
3. Click reset all to defaults
4. Note that all colors are now changed to not what the defaults are (eeschema seems to go all white with a black preview)

KiCad Version

Application: Eeschema
Version: (5.99.0-2213-ge3af9a761a-dirty), debug build
Libraries:
	wxWidgets 3.1.3
	libcurl/7.69.1 OpenSSL/1.1.1g-fips zlib/1.2.11 brotli/1.0.7 libidn2/2.3.0 libpsl/0.21.0 (+libidn2/2.3.0) libssh/0.9.4/openssl/zlib nghttp2/1.41.0
Platform: Linux 5.6.19-300.fc32.x86_64 x86_64, 64 bit, Little endian, wxGTK
Build Info:
	Build date: Jul  7 2020 01:59:59
	wxWidgets: 3.1.3 (wchar_t,wx containers) GTK+ 3.24
	Boost: 1.69.0
	OCC: 7.4.0
	Curl: 7.69.1
	Compiler: Clang 10.0.0 with C++ ABI 1002

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