Seg fault running progress dialog for Fill All Zones

[Jeff Young]

I get a seg fault on OSX when using 'b' in pcbnew to fill all zones. The progress dialog comes up but then hangs.

Crash report attached.

Application: kicad
Version: (2017-12-06 revision ee56e21)-master, release build
Libraries:
    wxWidgets 3.0.2
    libcurl/7.54.0 LibreSSL/2.0.20 zlib/1.2.11 nghttp2/1.24.0
Platform: Mac OS X (Darwin 17.2.0 x86_64), 64 bit, Little endian, wxMac
Build Info:
    wxWidgets: 3.0.2 (UTF-8,STL containers,compatible with 2.8)
    Boost: 1.61.0
    Curl: 7.43.0
    Compiler: Clang 7.3.0 with C++ ABI 1002

Build settings:
    USE_WX_GRAPHICS_CONTEXT=ON
    USE_WX_OVERLAY=ON
    KICAD_SCRIPTING=ON
    KICAD_SCRIPTING_MODULES=ON
    KICAD_SCRIPTING_WXPYTHON=ON
    KICAD_SCRIPTING_ACTION_MENU=ON
    BUILD_GITHUB_PLUGIN=ON
    KICAD_USE_OCE=ON
    KICAD_SPICE=ON

[Jeff Young (jeyjey)]

Patch submitted to the email list. https://lists.launchpad.net/kicad-developers/msg32399.html

Note that I suspect this all has to do with the fact that we run the progress updater in parallel (and it, in turn, runs the event loop to dispatch UI events).

We update the progress directly between each step of filling the zones, so the parallel thread only updates the elapsed time counter between each step. Is this really worth the headache of multi-threading and re-entrant event loops?