So now I just need to figure out why my mingw-built binaries work fine on mingw-built perl, but crash on exit when run on ActivePerl
BrowserUk established that the crash was occurring in the libgcc_s_dw2-1.dll ... and that piece of information made the job of fixing the problem so much easier.
Most of my ppm packages have a dependency on libgcc_s_dw2-1.dll, so I therefore distribute that file with them.
But rather than have ppm install individual copies of that dll for each module that needs it, I usually just place it in blib/script (for all module packages, whether they need it or not) - so that it gets installed into either perl/bin or perl/site/bin. That way the user only ever has the one copy of that file installed.
It's not a large file, so packaging it with every ppm is not terribly wasteful. For that matter, it probably wouldn't matter if each module *did* have its own copy of libgcc_s_dw2-1.dll ... but that doesn't fit too well with *my* idea of tidiness.
However, I don't like the idea of installing that dll into a path folder (which is where it needs to go) - given that there could well be other instances of that dll elsewhere in the path, thereby causing some incompatibility.
So, I rename a copy of libgcc_s_dw2-1.dll to libgcc_sis_452.dll, have the module look for that dll instead, and distribute (in blib/script of the ppm package) libgcc_sis_452.dll instead of libgcc_s_dw2-1.dll. (I also take a similar approach with libstdc++-6.dll which I've renamed to cpp+-6_sis.dll, but I distribute that file only with the few packages that actually need it.)
One drawback with that is that, having 'ppm install'ed one of my packages, you then need to use '--force' with future 'ppm installs' of any other of my packages - otherwise the installation fails because ppm won't overwrite a file (namely, perl/site/bin/libgcc_sis_452.dll) that was installed by another ppm package.
So ... getting back to the cause of the crash ... I knew that there was no problem with libgcc_s_dw2-1.dll, because I had been using and distributing it (albeit under a different name) for quite some time ... yet, here it was, causing a problem.
I think this happened because *both* libgcc_sis_452.dll and libgcc_s_dw2-1.dll were being loaded by the application. In effect, the same dll was being loaded *twice*.
Restructuring the building of Gtk2-WebKit-0.09 such that there's no dependency on any dll named libgcc_s_dw2-1.dll fixes the problem for me.
Thanks yet again, Buk. If you've a mind to check that it works ok for you, just
ppm install http://www.sisyphusion.tk/ppm/Gtk2-WebKit.ppd --force
and add perl/site/bin to your path.
It's a bit annoying that Perl/site/bin doesn't get added to the path by default ... I wonder if there's a folder in the blib where I can place libgcc_sis_452.dll in order that it will invariably end up in perl/bin ?
And thanks to Hans Oesterholt, who prodded me into getting this done - and even located the requisite (pre-built) libraries for me.