Choose Footprint dialog list selection issue

[Stou Sandalski]

The "Choose Footprint" Dialog box doesn't show the correct footprint when you mouse over the list if a search resulted in more than one screen of footprints. If only a few items are shown the issue doesn't appear.

Steps to replicate:

1. Place > Footprint
2. Type `Re` and move the mouse over the list to select a footprint
3. Notice that as you mouse over and item it changes to the item above it.

Attached is a screen recording of the issue.

Application: kicad
Version: (5.1.0-rc1-121-g04e593a60), release build
Libraries:
    wxWidgets 3.0.4
    libcurl/7.61.1 OpenSSL/1.1.1a zlib/1.2.11 brotli/1.0.5 libidn2/2.0.5 libpsl/0.20.2 (+libidn2/2.0.5) libssh/0.8.6/openssl/zlib nghttp2/1.34.0
Platform: Linux 4.20.6-200.fc29.x86_64 x86_64, 64 bit, Little endian, wxGTK
Build Info:
    wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8) GTK+ 3.24
    Boost: 1.66.0
    OpenCASCADE Community Edition: 6.9.1
    Curl: 7.61.1
    Compiler: GCC 8.2.1 with C++ ABI 1013

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=OFF