Fix msvc build

[andy5995]

Written by Claude with Andy's permission

Summary

A Windows build is moderately feasible but requires source-level work before CI can be added. The main application code is already largely portable; the effort is in wiring up ClanLib's existing Win32 backends and removing hardcoded X11 dependencies from the build system.

What already exists

ClanLib (bundled in external/clanlib/) already has Win32 backends written:

• Application/Win32/clanapp.cpp — Windows entry point
• Core/System/Win32/ — threading, mutexes, event handling
• Display/Win32/ — Windows display and input
• GL/WGL/ — Windows OpenGL

The main application code (lib/, ruby/, netpanzer/) has no POSIX-specific APIs and already has a #ifdef WIN32 stub in lib/flexlay.cpp.

What needs changing

1. external/clanlib/SConstruct — platform-aware source selection

Currently hardcoded to compile Unix/GLX sources. Needs sys.platform detection to select Win32 sources instead.

2. Root SConstruct — remove hardcoded X11 link flags

# Currently hardcoded:
LIBS=[..., 'X11', 'Xmu', 'GL', 'GLU', 'png', 'jpeg', 'Xxf86vm', 'Xi']

On Windows: drop the X11 libs, link against opengl32, gdi32, user32 etc. There is even a FIXME comment in the file acknowledging this.

3. Launcher scripts

netpanzer/netpanzer-editor is a shell script. A .bat / .cmd equivalent is needed that sets PATH instead of LD_LIBRARY_PATH.

4. CI (.github/workflows/c-cpp.yml)

Adding a windows-latest matrix entry is straightforward after the above is done. The current CI uses apt and X11 dev packages which don't exist on Windows, so CI cannot be added until the source-level port is complete. MSYS2 on the runner could provide GCC and some packages, but X11 headers are not available on Windows regardless.

Effort estimate

Area	Effort
ClanLib SConstruct platform detection	4–6 h
Root SConstruct X11 abstraction	2–3 h
Launcher .bat scripts	1 h
CI workflow addition	1 h
Testing / debugging	4–8 h
Total	~12–19 h

Not required

• Rewriting ClanLib platform code (already done)
• Porting the Ruby scripting layer (SWIG and Ruby are cross-platform)
• Porting Boost usage (header-only shared_ptr, cross-platform)

[andy5995]

Linux build works in #3

[andy5995]

The above is mostly outdated since the editor has been ported to Qt, but currently the build is failing on MSVC.

[5](https://github.com/netpanzer/flexlay-netpanzer-map-editor/actions/runs/24481386241/job/71546498498#step:8:76)
meson.build:18:16: ERROR: Dependency lookup for qt5 with method 'config-tool'
failed: 'NoneType' object has no attribute 'extend'