Sporadic ghost pixels on pcbnew right toolbar

Description

Pcbnew right hand toolbar doesn't always repaint correctly and leaves some "ghost" pixels of the icons when the window size is increased.

Steps to reproduce

Open pcbnew window and drag it's corner with a bit of speed. Sometimes the ghost pixels are cleared, sometimes they remain after you stop dragging.

KiCad Version

Application: KiCad
Version: (5.1.8)-1, release build
Libraries:
    wxWidgets 3.0.5
    libcurl/7.71.0 OpenSSL/1.1.1g (Schannel) zlib/1.2.11 brotli/1.0.7 libidn2/2.3.0 libpsl/0.21.0 (+libidn2/2.3.0) libssh2/1.9.0 nghttp2/1.41.0
Platform: Windows 8 (build 9200), 64-bit edition, 64 bit, Little endian, wxMSW
Build Info:
    wxWidgets: 3.0.5 (wchar_t,wx containers,compatible with 2.8)
    Boost: 1.73.0
    OpenCASCADE Community Edition: 6.9.1
    Curl: 7.71.0
    Compiler: GCC 10.2.0 with C++ ABI 1014

Build settings:
    USE_WX_GRAPHICS_CONTEXT=OFF
    USE_WX_OVERLAY=OFF
    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

This doesn't happen on latest 5.99.