Color-theme combobox in Symbol Editor > Color Options preference is not wide enough

Start KiCad and open the Symbol Editor. Select Preferences menu entry. In the dialog box that pops up click the Color Options entry in the left side. On the right side the button to select the theme is not wide enough. The text on the the left side is cut off. If you click the selector button it becomes wider, extending beyond the area for the Color Theme box, and shows you the full text of the available options.

Application: KiCad
Version: (5.99.0-1660-g050191460-dirty), debug build
Libraries:
    wxWidgets 3.0.4
    libcurl/7.58.0 GnuTLS/3.5.18 zlib/1.2.11 libidn2/2.0.4 libpsl/0.19.1 (+libidn2/2.0.4) nghttp2/1.30.0 librtmp/2.3
Platform: Linux 4.15.0-99-generic x86_64, 64 bit, Little endian, wxGTK
Build Info:
    Build date: May 13 2020 10:31:00
    wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8) GTK+ 3.22
    Boost: 1.65.1
    OpenCASCADE Community Edition: 6.9.1
    Curl: 7.58.0
    Compiler: GCC 7.5.0 with C++ ABI 1011

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=OFF
    KICAD_STDLIB_DEBUG=OFF
    KICAD_STDLIB_LIGHT_DEBUG=OFF
    KICAD_SANITIZE=OFF