Jack,
The lack of stdcall has caused both CLISP and LispWorks to crash for me when I use the Win32 EnumChildWindows API function, which takes a callback that must be declared as stdcall [1] I can provide a self-contained testcase that demonstrates the problem, if that would be helpful.
I'd like to add this to the CLISP testsuite. I don't know the MS-Windows APIs and never looked for a testcase. Indeed, it needs to involve callbacks to show the difference AFAIK.
Regards, Jörg Höhle.